Multiple mode personal wireless communications system

ABSTRACT

A multiple mode, personal, wireless communications system exists within a radiotelephone network serving general customers and provides additional services to a select group of customers. The system uses handsets (32) which automatically switch between a standard cellular radiotelephone mode of operation (1901) and an enhanced cordless mode (1420) when the handsets (32) are within range of pico cells (26) that are interconnected to the public switched telephone network (20). Each pico cell is controlled via a framework of overlay cells (10b) that operates independently of the radiotelephone network and uses a unique control protocol on a small number of reserved cellular channels. Each pico cell consists of a spectrally dynamic, non-capturing, frequency agile, multi-purpose base station (26) provided at customer-selected locations to cooperate with the overlay cell framework. Each pico cell is capable of supporting multiple handsets (32) and using low power operation that achieves limited coverage. Each pico cell reduces traffic on the standard cellular radiotelephone network by independently handling registered handsets (32). An alternate line option module (22) provides wireless local interconnect capability to selectively route call traffic between land lines (24) and the standard cellular radiotelephone network. Service control units (12) and host stations (17) facilitate wireless activation and control of each pico cell and handset (32) via the overlay cell framework.

RELATED APPLICATION

This patent application is a Continuation-In-Part of "Multiple ModePersonal Wireless Communications System," by Robert G. Zicker, et al.,Ser. No. 08/201,445, filed Feb. 24, 1994, now U.S. Pat. No. 5,594,782.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to an improved wireless communicationssystem. More particularly, the preferred embodiment of the inventionconcerns a multiple mode communications system, including specialhandsets designed to operate with standard analog or digital protocolswhen within the coverage of a standard cellular radiotelephone network,and to automatically switch to an enhanced cordless mode that operateswith unique protocols when within the coverage area provided byindependent, low power "pico" cells that are connected to the wirelinetelephone network. The term "pico" is used herein to suggest a smallersize than conventional cellular radio telephone cells. Pico cells areprovided at customer selected locations to cooperate with a framework ofoverlay cells that operate independently of the cells of the cellularnetwork.

This overlay cell framework allows the service provider to exercisecomplete control over the operation of each special handset and the picocell system by means of service control units and host stations. Thestandard cellular system can be further enhanced by the addition of zoneidentifier overhead messages which are ignored by standard handsets butinterpreted by the special handsets to inform those customerscontinuously of the special handset's current operating mode.

2. Description of Related Art

There has long been a recognized need for ubiquitous telecommunicationsservices wherein each customer is assigned a personal service number andprovided with suitable equipment which will permit the customer to havetwo-way communication capability (i.e., the ability to make and receivecalls) regardless of the customer's changing location.

Systems that extend beyond traditional wireline telephone service havebeen developed in order to more closely achieve this capability from atechnical perspective. For example, recent innovations in paging,standard cordless within the home telephone service, cellular telephoneservice and personal communications systems are well known. The designsof such systems all comprise efforts to cost effectively satisfy theneed for ultimate ubiquitous service. However, each system has wellrecognized technical and cost disadvantages which cause it to fall shortof providing ubiquitous telecommunications service.

For example, conventional systems control the operation of remoteequipment via remote programming. However, such conventional systemsrequire original programming to establish a phone system identity, suchas a Mobile Identification Number (MIN), which may be later used toengage in calls that provide remote programming. This is an undesirableremote programming technique because it prevents the originalprogramming from occurring remotely. Consequently, an entire complex andexpensive infrastructure is provided to deal with original programmingfor remote equipment through physical access to the equipment.

In addition, conventional cellular systems monitor power levels oftransmitted signals to determine whether signal levels are sufficientlyhigh to warrant the provision of communication services. Suchconventional systems have a relatively low access threshold because theydo not wish to deny communication services to any potential user andforego the revenues potentially achievable therefrom. However,conventional cellular systems may handoff or drop a call immediatelyafter accepting access from a handset with a weak signal. This is anundesirable technique when applied to small cells that do not supporthandoffs or wish to minimize handoff overhead communications because itleads to dropping or handing-off calls immediately upon access.

Furthermore, conventional cellular systems are designed so that usersare not aware when their calls are about to be dropped by a cell. When acall is dropped by one cell, hopefully another cell is available toaccept the call through a handoff process. But, in conventional andother cellular systems, the availability of another cell is not assured.This is an undesirable operational technique because calls are droppedwithout warning users in situations where users may be able to takesteps to prevent the call from being dropped.

Moreover, when conventional systems provide alerting signals, such ascall waiting sounds and others, to users during a call, such alertingsignals are often configured so that both parties to the call are awareof the alerting signal. This too is an undesirable operationaltechnique. The party in the call who is not being alerted generally hasno need to know of the alert. When this other party becomes aware of analert which has no meaning to him or her, confusion often results andthe flow of a conversation is often unnecessarily disrupted.

Still further, conventional systems are designed merely to provideservices through handsets when they are able to do so. They generallyfail to recognize that a variety of communication services may beavailable through a variety of different communication systems, such asmultiple cellular systems and a land-line service. They further fail tointegrate the variety of services in a common handset and to providemeaningful information to a user regarding the various communicationservice options which may be available through the handset from time totime.

Accordingly, a need still exists for an improved communications systemthat comes closer to providing ubiquitous communications service tocustomers than existing systems.

Related Patents

U.S. Pat. No. 5,046,082, entitled "Remote Accessing System for CellularTelephones," assigned to the assignee of the present invention, byRobert G. Zicker et. al. relates generally to improvements intelecommunications systems or service.

SUMMARY OF INVENTION

Therefore, it is an object of this invention to provide an improvedtelecommunications system which more completely meets customer needs forlow cost, ubiquitous telecommunications service.

It is another object of the invention to provide an improvedtelecommunications system, designed to include a standard cellularnetwork, and which further includes a network of overlay cells thatoperate independently of the cells of the cellular network.

It is a further object of the invention to provide, in such a system, amulti-channel pico station at each customer location that, in turn,supports multiple portable telephone handsets, with each handset beingcapable of operating in a wireless or pico mode when within the customerpremises, and in a standard cellular mode when away from the customerpremises and yet within the cellular coverage area.

It is yet a further object of the invention to provide such an improvedtelecommunications system wherein call forwarding capability is providedin conjunction with distinctive ring so that a customer with a portablepersonal handset selected to operate in one of the dual modes canreceive and readily identify incoming calls, directed to the assignedcellular customer number, through the unselected or inactive mode of thEsystem.

It is yet another object of the invention to provide automaticregistration and control of such a dual mode portable handset, withoutcustomer action, and with the customer being provided with a displayadvising the status or mode which the handset is set to operate in atany time, so that the customer can make informed, cost-effectivedecisions as to call placement.

It is another object of the invention to provide in a dual mode systemusing one radio per handset, a mode of operation based upon a unique,though cellular compatible, protocol that permits easy dynamic channelallocation and occupancy.

It is another object of the invention to provide an alternate lineoption capability which permits selective allocation of call trafficbetween the customer premises and the cellular network.

These objects and other features and advantages of the invention areattained in a telecommunications system that is designed to operate inconjunction with a standard cellular network having multiple cell sitesof either analog or digital configuration and embodying standardgeographical coverage. The system also includes a comparable network ofoverlay cells that operate independently of the standard cell sites ofthe cellular network. Alternatively, the system could be used within aradiotelephone network of other character, such as an SMR network, forexample.

Preferably, each overlay cell provides radio communication coverage to ageographical area that corresponds generally to the cellular site area,but on a set of reserved cellular frequencies that are selected with themaximum possible separation with respect to the assigned cellularnetwork signaling frequencies, so as to be non-interfering.

To cooperate with the overlay cells a base station, referred tohereinafter as a pico station, is provided at each customer site. Eachpico station is designed to support up to six improved portable handsetswhich function in dual modes. In a first mode each handset functions asa normal portable network or cellular telephone, when it is physicallyremoved from the proximity of the pico station. A second wireless modeof opEration is described herein for the handsets of the system whichhas been referred to herein as enhanced cordless on the first iterationsand will be referred to as the pico mode in subsequent usage. Theenhanced cordless mode of this invention differs from the operation ofstandard cordless telephones in several respects. This system employs aunique burst mode communication control protocol between the handsetsand the pico station which is not found in standard cordless operation.This protocol is compatible with cellular standards to permit dual modeoperation which would not be possible with standard cordless. Moreover,the standard cordless frequency arrangement is obviously different fromcellular frequencies used in this system. Other differences will becomeapparent from the description that follows, which result in operationalimprovements in the service offered.

The use of the unique protocol of this system permits remote activationand control using the 10k bit Manchester encoded data pathway inherentin cellular telephone hardware. Therefore, when close to the picostation, the handset operates as a cordless telephone supported by thepico station via a connection to the house PSTN wiring.

In the preferred mode, call delivery is provided through a link that mayalso include an alternate line option module connected between the picostation and the PSTN. With that arrangement, service can be providedthrough direct access from the pico station to the public switchedtelephone network, or alternatively, service from the pico station canbe selectively redirected back to the cellular network by the radio ofthe alternate line option module. A significant advantage of the systemarises from the capability of allocating selected portions of calltraffic between these two paths, in order to accommodate call capacityand varying call demand. This permits deployment of the system in areaswith limited cellular capacity, without necessitating rationing ofservice.

Service control units and a host station are provided to facilitate setup and control of the portable handsets and pico stations using remoteprogramming techniques which were not previously practical.

Each handset includes components comparable to that of a standard analogcellular telephone having one radio transceiver. In addition, thehandset has added software to permit it to operate in the pico mode, incooperation with the pico station located at the customer premises. Asan alternative to analog technology, the modified handsets can embodycompatible digital technology, again with the same necessary additionsor modifications to support pico operation.

After initial set-up, each handset employs a process to identify when itis in the general neighborhood of its authorizing pico station. Onlythen will the handset seek out its authorizing pico station byperiodically transmitting a signal to determine if it is withinacceptable communication range. If the pico station receives anacceptable level handset signal, it responds and exchanges registrationinformation with the handset to establish or register the handset in thepico mode.

The handset then sends a message to the cellular system upon which italso operates, directing that all incoming calls subsequently attemptedon the cellular network be forwarded to this authorizing pico stationtelephone number (this may be the customer home PSTN number). Finally,the handset is switched to the pico mode and sends a response controlmessage to the pico station indicating that it is "home" and in service.At that time, a message on the handset display indicates to the userthat the handset is in the pico mode, as opposed to the cellular mode.

When in the pico mode, the system operates at a lower power level onselected, reserved cellular channels with the same basic technicalstandards as analog AMPS type cellular systems. During this mode, thepico station can and does function as a telecommunications base stationwith no hand-off capability.

Up to six handsets may be registered with the pico station. In thepreferred embodiment only one handset may transmit at any one time.However, the system supports the capability for other handsets to joincalls in progress. The handset to pico station link is accomplished atvery low power levels during call activity, which results in low batterydrain.

The pico station is connected directly to home telephone wiring for calldelivery, but is always controlled via a radio frequency link to aservice control unit and an overlay host station located within thenetwork area. When the handset is carried out of range of the picostation in an operating state, it automatically switches back to thecellular mode and cancels any existing call forwarding.

It should be noted that operation of the special handsets and overlaynetwork of the invention is transparent to, and will not interfere with,standard cellular network operations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system block diagram of one preferred embodiment of thesystem of the invention;

FIG. 2 is a component diagram of a handset usable with the system of theinvention;

FIG. 3 is a diagram of a handset of the system illustrating the keypadlayout and other external features;

FIG. 4 is a component diagram of a pico station of the system;

FIG. 5 is a block diagram of a service control unit configuration of thesystem;

FIG. 6 is a component diagram of an alternate line option module usablewith the system of the invention;

FIG. 7 is a flow diagram of the operation of the pico station in the Setup and Activation function;

FIG. 8 is a flow diagram of the operation of the pico station in thepico station Configuration function;

FIG. 9 is a flow diagram of the operation of the pico station in thehandset Authorization function;

FIG. 10 is a flow diagram of the operation of pico station during theScan Channel function;

FIG. 11 is a flow diagram of pico station operation during Call and IdleLoop function;

FIG. 12 is a flow diagram of pico station operation during CallOrigination and Call Joining function;

FIG. 13 is a flow diagram of pico station operation during CallTermination function;

FIG. 14 is a flow diagram of handset operation during Initialization andservice determination function;

FIG. 15 is a flow diagram of handset operation during monitor picostation and find channel function;

FIG. 16 is a flow diagram of handset operation during handsetAuthorization function;

FIG. 17 is a flow diagram of handset operation during handsetRegistration function;

FIG. 18 is a flow diagram of handset operation during handset Reacquirepico station function;

FIG. 19 is a flow diagram of handset operation during handset cellularidle, speed dial, and cellular conversation functions;

FIG. 20 is a flow diagram of handset operation during dial number entryfunction;

FIG. 21 is a flow diagram of handset operation during numeric entry andnon-numeric entry function;

FIG. 22 is a flow diagram of handset operation during other portions ofcall selection and delivery function;

FIG. 23 is a flow diagram of handset operation during contact picostation function;

FIG. 24 is a flow diagram of handset operation during handset processbase order function;

FIG. 25 is a flow diagram of operation of the alternate line optionmodule during Initialization, Configuration, and Service Determinationfunction;

FIG. 26 is a flow diagram of operation of the alternate line optionmodule during call processing function;

FIG. 27 is a bit assignment chart of handset message formats for reversecontrol channel communications for components of the system operating inthe pico mode;

FIG. 28 is a bit assignment chart of pico station message formats forforward control channel overhead and registration command words forcomponents of the system operating in the pico mode;

FIG. 29 is a bit assignment chart of pico station message formats forforward control channel call processing commands and authorizationcommand words for components of the system operating in the pico mode;

FIG. 30 is a message framing chart for forward and reverse channelcommunication packets of the system;

FIG. 31 is a bit assignment chart of service control unit messageformats for reverse control channel setup and control command words forcommunications with the pico station on the overlay network;

FIG. 32 shows a flow diagram of a call connected process performed bythe pico station; and

FIG. 33 shows a flow diagram of a normal conversation function performedby the handset.

DETAILED DESCRIPTION OF THE INVENTION Systems Overview

The system of the invention includes a combination of elements thatproduce economical, convenient telecommunications services in the home,or at another customer site, as well as when the customer is away fromthe home site.

From the service provider point of view, the system of the invention isdesigned to provide a special service to a select group of customers,and yet operate in conjunction with and within a standard radiotelephonenetwork such as a cellular network of either analog or digitalconfiguration that concurrently supports regular cellular customers. Inaddition, the system generally includes an overlay cell networkgenerally corresponding to the cell sites within the cellular standardnetwork. The overlay cell network provides radio communication coverageto a geographical area that generally corresponds to the cellular sitearea, but on a set of reserved cellular frequencies that are selectedwith the maximum permitted separation with respect to the cellularsignaling frequencies, so as to be non-interfering. A pico station isprovided at each selected customer site to interact with a convenientlylocated overlay cell. The pico station receives calls from a specialhandset and transfers these calls through the house wiring to the PSTN.In this manner, the system is capable of supporting a wireless or picomode of operation for the select group of customers when they are attheir home or service site, in addition to the service provided on thestandard network.

The improved wireless communications system is capable of supportingmultiple, dual mode telephone handsets associated with each picostation, with each handset being capable of operating in a pico modewhen within the customer premises; and capabLe of operating in astandard or cellular mode when located away from the customer premises,and yet still within the standard or cellular network coverage. Theadvantage of this system is that it is able to handle a substantialincrease in call traffic since it permits efficient utilization of allthe facilities of the system.

The pico stations are spectrally dynamic, non-capturing, networktransparent, personal pico cells within the network.

System Components

Referring now to the drawings and particularly to FIG. 1, a preferredembodiment of the invention will be described. FIG. 1 shows one of manycellular switches or cell sites 10a of an existing cellular system. Thecell site could be configured for standard operation of AMPS, or TDMA orCDMA digital service, of conventional design. EIA or TIA Standard 553,defines Specifications for Mobile Station and Land Station compatibilityof Cellular Systems with which all licensed cellular operations withinthe United States comply. The system of this invention is intended toadhere to these standards or to be compatible therewith.

The cell site illustrated can also be the physical residence of anoverlay cell and antenna 10b which provide radio coverage of the samegeneral geographical area as the cellular site.

However, the overlay cell operates on a set of reserved frequencies thatare selected to have suitable frequency separation with respect to thecellular frequencies, so that they do not interfere with cellular radiooperations. At least one channel is reserved for command purposes only,and the other reserved channels can provide both call and commandcapability. In this regard, it should be further recognized that allcommunications from handset to pico station are on the reserved callchannels with the exception of authorization communications, whereasservice control unit to pico station communications are predominantlycommand channel only communications.

Standard cellular frequency allocations are specified in EIA-553 section2.1.1.1. In the preferred embodiment, the reserved common controlchannel selected for B-Side use is 799 which is the channel most removedfrom the B-Side signaling assignments. The reserved call channels forB-Side will typically be channels 798-789.

For A-Side usage, the reserved common control channel is 991 which isselected to obtain the maximum separation from the A-Side signalingassignments. The reserved call channels for A-Side will typically be992-1001. Clearly, fewer or additional channels could be reserved, withsix to twelve channels being a preferred range.

Alternatively, a separate geographically located array of overlay cellscould be utilized, as compared to cellular cells, as long as radiocoverage generally comparable to the geographic area of the relatedcellular network is attained.

A pico station 26 is provided at a customer location that isinterconnected with the PSTN by a cable passing through a standard RJ11interface connected to the existing house telephone wiring. In theembodiment illustrated, an alternate line option module 22 is connectedbetween the pico station and the PSTN 20 via a cable 24. The alternateline option module resides on or near a customer location, which mayrepresent a residential premises or a business premises in thispreferred embodiment. A standard wireline telephone handset or handsetscan be interconnected with the house wiring as shown, if desired,although such is not required. If desired, the alternate line optionmodule may be omitted from the system, or deployed selectively, with orwithout an associated pico station on the same premises. Thus, thealternate line option module is an independent device capable of usewith any device interfaced with the house wiring.

Up to six dual mode portable handsets (32a-f) are provided, each beingassociated with the pico station, and being capable of operation in dualmodes under the support of the pico station and control of a servicecontrol unit as will be explained in detail hereinafter.

In a first mode, each portable handset functions as a portable cellulartelephone operated through a direct wireless connection to cell 10a. Ina second mode, the handset functions as an enhanced cordless telephonesupported by the pico station at the customer premises. In the latter orpico mode, call delivery can be provided to the public switchedtelephone network via a connection from the pico station through thewired telephone service in the home, in effect using a combination ofwireless and PSTN support. If the alternate line option module isprovided in the system, it provides yet a further capability ofselectively channeling calls to and from the handset via the picostation, the alternate line option module, and over the cellular networkrepresented by cell 10a, on the indicated wireless link.

At least one service control unit 12 is provided for each overlay cell,associated with the system through a cabled connection to the cell site,and a personal computer 16 is associated with the service control unitalso via a cable connection. The service control unit is connectedthrough the PSTN and a cabled connection 14 to a host station 17 havinga work station 18 associated therewith. The host is further connectedvia a standard X.25 channel to a customer activation system 23, such asare commonly employed by cellular carriers to control the activation andprogramming of cellular handsets permitted to function on a givencellular network. The remote programming functions of the host systemare suitably fulfilled by a subsystem such as is described in U.S. Pat.No. 5,046,082, previously referred to, and hereby incorporated byreference.

Referring now to FIG. 3, a handset for the system is illustratedincluding an outer case 31, a keypad 32, an antenna 34, and a displayscreen 35. The keypad includes a standard twelve key portion 38, a powerswitch 39, and a clear key 40. The usual "send" key is replaced with agreen key 41 bearing a special logo and the "end" key is replaced with ared key 42 also marked with a special logo. The green or off hook key,when depressed, serves to initiate dial tone and start a call sequence.The red or on hook key 42, when depressed, terminates a call sequence.

The handsets vary from standard cellular exterior design only in thevariation of function keys 41, 42 and in that the handset providesprecision dial tone, through use of the standard DTMF generator of thehandset in accordance with flow processing control explained inconnection with FIG. 20, herein, since the handset does not contain asend key. The dial tone is used in conjunction with the North AmericanNumbering Plan function to detect completion of dialed number status.Consequently, the handset dial plan differs from standard cellulardialing in that the handset generates local dial tone immediately whenplaced off-hook to indicate to the user that service is available and acall can be placed. The dialing process then follows the standard PSTNpractices (of off-hook, dial tone, dial number, call progress,connection, conversation and on-hook), with which telephone customersare familiar.

The handset also includes the capability to display for the user whichmode of operation the handset is currently set to provide, i.e. pico orcellular. This information, as well as other message information, isdisplayed on the standard LCD display screen 35 on the handset (forexample, suitable messages would include, Wireless=Home #n; NeighborhoodCellular=Local; Cellular=PREMIUM). The displayed status informationallows the user to make informed decisions when placing or receivingcalls, especially if special service provider rate plans are available.

Referring now to FIG. 2, a component diagram for a handset isillustrated, which is similar to that of a conventional cellularhandset. An antenna 50 is connected to a duplexer 52, that is in turnconnected to a receiver section 54 and a transmitter section 55. Aspeaker 56 is connected to the receiver and a microphone 57 is connectedto the transmitter. A central processing unit 58 is interconnected withboth the receiver and transmitter sections by an input/output buss andby an address/data buss. A display processor/keypad section 59, is alsointerconnected to the I/O buss in conventional fashion. A non-volatilememory EEprom 53 is also interconnected to the A/D buss in conventionalfashion.

Each handset is assigned a unique Mobile Identification Number (MIN)that is used by the cellular system as the handset telephone number.When the handset transitions from the cellular system service to thepico station for pico mode service, the handset automatically informsthe cellular system to forward any incoming calls placed to its MIN tothe PSTN telephone number associated with the instant pico station it isswitching to. This process is reversed each time that the handsettransitions back into the cellular system service area and out of thepico station or pico mode service area, as is explained in connectionwith flow process descriptions hereinafter. The special functions of thehandset are accommodated by added software executed by the handsetcentral processor.

Referring now to FIG. 4, a component diagram for a pico station isillustrated, including an antenna 60, connected to a duplexer 62, thatis in turn connected to a receiver section 64 and a transmitter section65. A central processing unit 66 of standard configuration is provided,and a standard telephone line interface module 72 is connected to thereceiver section and the transmitter section by audio cables 68, 69respectively. The interface module is also connected to the housetelephone line which connects to an alternate line option module, ifdesired, as is illustrated in FIG. 1. An I/O buss is interconnectedbetween the transmitter and receiver section and the central processingunit, as is an address/data buss. Also connected to the A/D buss is anon-volatile EEprom 70. A status LED 73 and an authorization modepush-button 74 are respectively connected to the I/O buss.

The purpose of the pico station is to provide an interface between eachof its authorized handsets and the customer site PSTN telephone line, orthe cellular system if it is so configured. Each pico station isdesigned to support up to six handsets and each handset can beauthorized for use with up to three pico stations to provide customerflexibility. The pico station preferably operates in the cellularspectrum and always functions as the land station device duringcommunications sessions with the handset in the pico mode. However,unlike standard cellular land stations, the pico station operates in apico mode and does not transmit a continuous overhead message datastream on a known channel for the handset to lock onto. Instead, thepico station and each handset utilize a unique operating protocol withburst mode communication to locate and access each other only whencommunication between those specific units is desired. This results insignificant system improvement in that channel usage is dedicatedprimarily to call exchange. In addition, handset battery capacity isconserved.

This unique operating protocol is initiated by the originating device(either the pico station or the handset) after the originating deviceselects a communications channel from one of the plurality of reservedchannels. The channel selection process is dependent upon theoriginating device measuring the strength of any signal present on theselected channel and comparing this measurement to a predeterminedacceptable value. If the signal present on the selected channel is lessthan this predetermined value, the channel is considered to be availablefor this communications session. If the level is greater than the knownvalue, the originating device selects another channel from the pluralityof known communications channels and performs the measurement andcomparison procedure again, until an acceptable channel is located. Theselected channel is occupied only for the duration of the communicationssession and then vacated. Once it is vacated, any nearby pico station orhandset that was avoiding this channel due to measured signal presence,can now use the channel for a corresponding communications session, andthen release it in turn.

Both the pico station and handset utilize very low transmit power. Thisfact, coupled with the unique channel selection process and otheradvantages of the system, allows a relatively small number of channelsto serve a very large population of customer sites. Another benefit ofthe dynamic channel selection and usage protocol is the elimination ofeffort currently required to preassign radio channels in adjacent picocell areas to avoid interference that is experienced in standardcellular land station systems. This elimination of frequency planningsimplifies the deployment of the system, allows it to be usedsuccessfully in neighborhoods, and allows the public to rapidly availitself of the benefits this system provides.

Activation and positive control of the pico station is maintained by thecellular service provider through the use of a service control unit suchas that illustrated in FIG. 5.

Referring now to FIG. 5, it includes a number of elements that areillustrated in FIG. 1, being designated by like numbers in FIG. 5. FIG.5 illustrates, in addition, a mobile service control unit 80 useful withfixed unit 12. Unit 80 comprises a mobile vehicle including a personalcomputer 80a interconnected with a cellular mobile radio unit 80b havinga design similar to a handset, particularly in that it further includesthe necessary software capability to perform pico mode overhead controloperations in addition to standard cellular overhead protocols.

In the embodiment illustrated, the mobile unit provides service controlunit function to pico stations which may be out of reach of a fixedservice control unit; or alternatively mobile units can be used in lieuof a fixed service control unit such as is indicated by numeral 12. Whena mobile service control unit is utilized, it operates with acommunication path from host station 17 through the PSTN to cellularcell site 10a. A communications path is then established between cellsite 10a and unit 80 via a standard cellular wireless link. Tocommunicate with and to control a pico station, unit 80 uses a wirelesslink on one of the pico frequencies that is selected to be the dedicatedcontrol channel identified as a common setup and control channelhereinafter. This wireless link follows a unique communication protocolas described in detail hereinafter which is compatible with the picomode protocols, but is a special subset thereof. The message formats forthis protocol are illustrated, in particular, in FIG. 31.

When the fixed service control unit 12 is utilized, a transmission linkfrom host station 17 through the PSTN to the service control unit isutilized. In addition, the service control unit is connected via a cableto cell 10b of the system. Communication from the service control unitto the pico station is then effected via a wireless link from cell 10bto the pico station using the dedicated control channel and the wordoperating protocol illustrated in FIG. 31.

It should be apparent that the fixed service control unit would be thepreferable manner of communicating with pico stations. However, in theinitial stages of installation of a system where gaps exist in theoverlay network, it may be necessary to use one or more mobile units.Alternatively, both mobile units and fixed units could be usedinterchangeably or in the same general area. It should also berecognized that when a mobile unit is utilized, it can depend entirelyupon transmissions from the host station or it can convey to theselected pico station information which is preloaded in the mobile unitby cassette or other media loaded on the PC. The same capability ispossible for the fixed service control unit.

At a minimum, one of these devices needs to be located within each cellsite serving the neighborhood in which the pico station is deployed.With essentially ubiquitous cellular system coverage, every household inan urban or suburban area is illuminated with cellular radio energy.(Most rural households also fall within the service contour of a typicalcellular provider and could also be provided with this service option).The service control unit capitalizes on this situation to contact anypico station within its territory using the reserved channel wirelesslink between cell 10b and the pico station to activate, update, auditand control its functions and operation.

Like the handset in the pico mode, the control unit also utilizes aunique operating protocol during its communications sessions with thepico station. These sessions, however, always occur on the commoncontrol channel reserved for this purpose. Service control unitinitiated activation sessions remain entirely on the common controlchannel. All other control unit sessions are initiated on any idlechannel within the desired pico station's known multiple channels, andthen move immediately to the common control channel for culmination. Anypico station can also initiate a session with the control unit bytransmitting its request on the common control channel whenever thischannel is idle.

The service control unit is linked to a centralized host station whichmaintains a data record of all active pico stations and handsets withinthe cellular carrier's service area. The host station, in turn, islinked to the central cellular customer activation system (of thecarrier) through which the host station receives data on the sale ofeach pico station and handset. This data is utilized by the host stationduring activation of each pico station and for control of the servicesprovided. Through the customer activation system, the host station alsois updated with changes to the customer's service profile. These updatesare immediately passed by the host station to the appropriate picostation via the control unit.

The elements of the alternate line option module are depicted in FIG. 6.As shown, the PSTN is connected via cable 82 to a network interfacedevice 83. The network interface device is provided by the localexchange carrier as the demarcation device between the local exchangecarrier facilities and the house wiring within the customer premises. Atelephone line interface module 84 is connected to the output of thenetwork interface device via cable 24. Connection to the house wiring 86is provided from the output of the telephone line interface module viacable 25.

The alternate line option module contains a central processor unit 97which controls all of the elements of the alternate line option via theinput/output buss 99 and the address/data buss 98. The controlledelements are the cellular receiver unit 88, cellular transmitter unit91, a talk battery substitution module 96, a 90 vac ring voltagegenerator 95, a precision dial tone generator 94, red/green status LED101, remote programming modem 104, real-time clock 106 and telephoneline interface module 84.

The cellular receiver 88 and transmitter 91 are connected to the antennaduplexer 93 through cables 89 and 92 respectively. The duplexer 93 isalso connected to the captive antenna 100 through cable 105. An audiopathway for receive audio to the telephone line interface module isprovided by conductor 87. The transmit audio pathway is via conductor90.

The central processing unit 97 has an integral microprocessor which alsocontains RAM for working registers, ROM for program storage and EEpromfor non-volatile data storage.

The alternate line option is normally powered from the ac power supply102 but it also contains a back-up battery 103 capable of providingabout one hour of continuous operation in the event of ac power failure.

System Protocols

All overlay network and pico mode operational protocols of the systemare implemented via a common air interface which utilizes a 10 K bitManchester encoded data transmission methodology integraL to cellulartelephony. This implementation allows for less expensive hardware sinceprocessing of 10 K bit data messages is already a requirement for allcellular stations. consequently, no additional hardware need be added tothe handsets to accommodate this protocol.

The system message format is consistent with standard cellular telephoneformat, but message contents are unique between the overlay networkelements. Overlay network elements always utilize channels that arereserved exclusively for them while they are communicating with eachother. Therefore, compatibility has been provided between currentcellular protocols and the protocols of this new system. The benefit ofsuch an implementation lies in the fact that any of a multitude ofexisting cellular telephone manufacturers can supply handsets simply bymodifying their operating handset software to support the added overlaynetwork protocols.

In the cellular mode, the base station acts as the land station andprovides control over all transmissions of both land station andhandset. In the pico mode, the unique protocol establishes the handsetand pico station in a first to initiate, control relationship.Specifically, on outbound calls directed to the handset, the picostation has dominant control under the protocol. With respect to inboundcalls, the handset exercises the dominant control under the protocol.

In the service control unit-pico station relationship, the servicecontrol unit is the master and the link between those units consists ofthe 10 k bit Manchester encoded data stream. It should be recognizedthat this is a reverse hierarchy of control as compared to existingcellular systems.

In the host-service control unit relationship, the host exerts thedominant control influence and initiates messages based upon the trafficavailability. As described in U.S. Pat. No. 5,046,082, thecommunications connection between these units follows a modem based dialup protocol using a unique DTMF arrangement.

The direct application of this patented technique for remote programminghas been improved in the present system through the elimination of datamodem requirements in the downloading operations of the system controlunit-pico station link. The modem requirement is further eliminated inthe pico station-handset link during downloading operations. This isaccomplished by transforming the unique DTMF modem access activationcommand sequence that the service control unit receives from the hostinto parameter information message formats of the unique enhanced orpico protocol.

The same message formats are then used in remotely programming thehandset. Consequently, the handsets are no longer required to contain aninband modem. This elimination of hardware removes a previously existingpractical constraint from this system against the use of remoteprogramming on handsets. This, in turn, makes remote programming ofhandsets cost effective.

With the system as presently configured, it is intended that each memberof the household will have a handset assigned for his or her personaluse. With the system in its presently described configuration, only asingle call can be in process at any one time. However, provision ismade for more than one handset to be interconnected to a given call.

Other options are described hereinafter with respect to alternateembodiments. In addition, a distinct ringing capability is describedsuch that family members can readily distinguish incoming personalcalls.

Each handset is intended to operate in a standard cellular mode whenaway from the pico station. That operational mode of the handsetutilizes the standard cellular overhead messaging protocol of thecellular system. When the handset is brought back within the range ofthe pico station, it automatically switches to the pico mode undersupervision of the pico station. Then the handset operates on the uniquecontrol protocol supported by the pico station.

In view of these features, it is necessary for the system to includemeans for both set-up and operation of the handset in each of the twomodes. Furthermore, a unique transition protocol is required in order toenable automatic control and switching of the handset between the twooperational modes.

In order to describe all the protocols necessary to operate the systemof the invention, the steps necessary to place the handsets and the picostation in use after purchase by a customer are generally describedhereinafter. The first step generally involves Activation of the picostation. The procedure for the handsets then involves an Authorizationprocess which is the procedure followed by the customer and the cellularservice provider following purchase of the pico station and handset.

These procedures of Activation and Authorization include both the usualcustomer activation process tasks necessary for operation of handsets inthe cellular mode, and special steps which are necessary to set up thepico station and each handset purchased for operation in the pico mode.In addition, the customer must authorize each purchased handset for usewith its associated pico stations. Handsets will register automaticallywhen in communications range of the pico station.

As a precursor to Registration of each handset to a pico station, thereis a recurring process referred to as Location Analysis, whereby eachhandset detects that it is in a cellular coverage area of the cell sitethat also covers one of its authorized pico stations. This alerts thehandset that it is in its home neighborhood and may now be within radiorange of the pico station with which it is authorized to function. Onlythen will the handset attempt to contact its authorizing pico station.This location analysis process occurs automatically each time thehandset is placed in use, and constantly during its cooperation with thecellular system if the handset is moved from location to location by thecustomer. Its use within the system eliminates a substantial amount ofcrosstalk or interference that inherently exists under other dual modesystems being considered in the industry. In addition, location analysisconserves handset battery capacity and enhances call traffic capacity ofthe reserved channels.

After successful Registration in the pico mode, the handset operates invarious states. A Reacquire function is performed periodically by thehandset to maintain the handset's registered status with the picostation. This process is timer activated and is another burst modecommunication process designed to limit channel usage fornon-conversation purposes, as explained in the FIG. 18 flow process. Inan idle state, the handset is available for general use. In addition,the handset is capable of joining a call in progress, capable of a callorigination process, and capable of a call termination process, throughspecific process task flows 1that are described in detail hereinafter.

As previously explained, when purchased the pico station is not yetactivated for use by the consumer. The Activation process is performed"over the air" by one of the service control units. The cellular carrierproviding the pico station service selects and reserves a single controlchannel for use by all service control units and pico stations. Thiscommon control channel is known to the pico station. Each pico stationis also assigned a unique 22 bit electronic serial number (ESN) by themanufacturer. The pico station ESN is captured at the point of sale bythe customer activation system and transmitted to the selected systemhost station along with the address and telephone number of the locationwhere the pico station is intended for use. The customer activationsystem also transmits to the host station the MIN and ESN of eachhandset which is authorized to use this pico station.

In response, the host station examines the pico station location addressand selects the most appropriate service control units for contact withthe pico station. The host station then issues a command to theseselected service control units ordering a Locate task of the target picostation to be executed.

The involved service control units then each periodically issue on thecommon control channel, an Undeniable Access Message addressed to thetargeted pico station as identified by its ESN. This process is repeateduntil contact with the targeted pico station is achieved.

It should be recognized that the Undeniable Access Message ESN fieldcould additionally be partially or wholly encoded, using variouspublic-private key arrangements. If used, such encoding provides acontrol access security capability to the cellular service providerwhich can be used alone or in combination with the security inherent inthe described remote programming system access arrangement, therebyyielding a double level of security protection.

In order to receive the Undeniable Access Message when the consumerinstalls the pico station at the intended location and connects itspower supply, the pico station will immediately enter an Initializationtask. The central processor of the pico station then performs internalhousekeeping chores to place the pico station radio and telephone linein an idle state. The central processor of the pico station then uploadsthe contents of its EEprom to determine the pico station operationalstatus. If the pico station is not yet configured, a Pre-Configurationtask is entered. In that event, the central processor instructs the picostation radio to alternately tune to the known A-side, and then theB-side control channel to check for contact from the service controlunit.

Upon receipt of an Undeniable Access Message addressed to its picostation ESN, the pico station transmits, at its full power, aCommunication Setup Message (ACK) to the service control unit. When theACK is received, the service control unit measures the received signalstrength of this pico station ACK signal and issues an End Sessioncommand to the pico station. The service control unit then reports tothe host station the results of its Locate task.

The host station, in turn, analyzes the results from all instructedservice control units and selects the one reporting the highest ACKsignal strength to be the service control unit to server this picostation location.

This location verification process ensures the cellular service providerthat the customer supplied address information is correct, as eachUndeniable Access Message is targeted to a specific portion of theoverall cellular system coverage. The host station then transmits to theselected service control unit all operating parameters that need to beforwarded to the selected pico station. This data is transmitted in theform of an Activation Command Sequence.

Upon receipt of an Activation Command Sequence, the selected servicecontrol unit queues up a pico station Configuration session for thetargeted pico station. The service control unit initiates this sessionby first transmitting an Undeniable Access Message addressed to thetargeted pico station. Upon receipt of the corresponding pico stationACK, the service control unit will pass to the pico station theparameter information defined in a Parameter Information Message formatdescribed hereinafter.

The pico station again replies with an ACK message upon receipt of eachParameter Information message. A Non-Acknowledge (NAK) message from thepico station results in the service control unit retransmitting theParameter Information message again. When all messages are successfullytransmitted, the control unit issues an End Session command to tile picostation. The service control unit then reports the successful activationprocess status of this pico station to the host station and saves to itsmemory a data file for this pico station containing the assignedparameters.

The consumer must also Authorize each handset for use with the picostation. This process is instituted to prevent unauthorized usage of thepico station and the associated telephone line. To initiate thisprocess, the handset must be powered on and the "Base Station auth"selection made from the handset menu function. The handset must then bebrought into close proximity of the pico station, since the process isperformed at extremely low transmit power levels to preventunintentional access to any other nearby pico station.

Accordingly, the pico station, upon receipt of its configuration, entersa Pre-Authorization status, and awaits depression of its authorizationbutton, or further contact from the service control unit. The picostation changes the associated status LED from red to green.

The customer then depresses the authorization button on the pico stationuntil the associated status LED flashes green to indicate that theprocess has been initiated. The handset display will also flash whilethe authorization session is in progress. The handset must remain inclose proximity to the pico station for three to seven seconds ofprocess duration. The pico station utilizes the known common controlchannel for this Authorization process exchange.

During the authorization process, the pico station captures and verifiesthe MIN and ESN of the handset against the list of allowable handsets itreceived from the service control unit. Should a given handset not be onthe list, the process related to it is aborted without authorizing thehandset. If the handset was expected, the pico station will pass to itthe parameter information listed utilizing the Parameter InformationMessage format described hereinafter.

The handset sends an ACK message response for each Parameter InformationMessage as it is received. Should the handset NAK a message, the picostation will retransmit that message. Upon completion of all messages,the pico station issues an End Session command to the handset toterminate the process. This returns the status LED of the pico stationto a steady green condition, to indicate the end of the process. Thehandset and pico station then return to their respective Idle states.

Certain messages are referred to in the process flow descriptions ofFIGS. 7-26. These messages are all constructed of words illustrated inFIGS. 27-31, as previously indicated.

FIG. 27 depicts the generalized formats for handset special data messagewords utilized during the pico mode of operation. Items are shown withreference to their actual position in a data message sent from thehandset to the pico station over the reverse channel direction of thechannel in use.

All words depicted in the Figure follow the general format requirementsof EIA-553 Standard--Mobile Station--Land Station CompatibilitySpecification.

A handset data message may consist of one, two or three words sent as apacket on the reverse channel to pass communications to the picostation. The word position assignment for each item of FIG. 27 is alwaysthe word position that particular data word will assume in the createddata message, as indicated by the word number. Each of the illustratedfields within a depicted word is identified with the standarddesignation for that field as specified by EIA-553.

In order to facilitate the understanding of the message wordsillustrated, certain key fields are explained herein.

The Field NAWC=Number of Additional Words Coming and will reflect thetotal remaining word count in every transmitted message word. The orderfield, when included in a word, shall always be set to 11110 whichindicates a Local order which is not to be confused with a Networkorder. The field ORDQ=Order Qualifier and is set to 000 in all casesexcept the Best Server and Parameter Information commands where it isset to 001. The field Local, when included in a word shall contain thefive bit Local Order pattern identifying the specific command to beexecuted.

It should be recognized that all FIG. 27 words are directed only to thepico station, and never to the cellular network. Item 2701 is known asthe Abbreviated Address Word and is utilized as a single word commandresponse message; the first word of each two word Access Attemptmessage; and the first word of each three word Identification commandresponse message.

Access Attempt messages are used for Authorization, Registration,Re-Acquisition, Call Origination and Call Termination events. Tofacilitate the understanding and identification of the specific messagesinvolved in each communications process, the messages related to FIG. 27are therefore listed hereinafter. The Authorization Access Attemptmessage consists of 2701 (word 1) and 2707 (word 2) sent as a two wordmessage (I'll Take It). The initial Registration Access message consistsof 2701 (word 1) and 2703 (word 2) sent ets a two word message (Here IAm1). The handset Re-Acquisition Access message from the handsetconsists of 2701 (word 1) and 2704 (word 2) sent as a two word message(Here I Am2). The handset Call Origination Access attempt that occursprior to collection of the dialed number consists of 2701 (word 1) and2705 (word 2) sent as a two word message (I Want In1). The handset CallOrigination Access demand message that occurs after dialed numbercollection consists of 2701 (word 1) and 2706 (word 2) sent as the firsttwo words in the message (I Want In2). The handset Call TerminationAccess Attempt message consists of 2701 (word 1) and 2707 (word 2) sentas a two word message (I'll Take It).

Item 2702 is known as the Parameter Information Acknowledgment word andis always sent as a one word message in response to the pico stationduring the Authorization process of downloading the handset with theoperating parameters needed for pico mode operation. This single wordresponse message utilizes bit positions 26 through 36 to ACK or NAKreceipt of a Parameter Information message from the pico station. Bit 26(X) is set to 0 to indicate ACK and 1 to indicate NAK. Bits 27 and 28(AA) are set to 00 to ACK/NAK last order and 01 to ACK/NAK lastParameter word. Bits 29 through 36 (ZZZZZZZZ) are set to the ParameterInformation Identity (PID) of the NAK'd data.

Item 2708 is known as the Best Server response and the eight bits, 19through 26, are encoded as follows: bits 19 & 20 (DD)=Digital Color Codeof the Best Server (0 to 3); bit 21=0; bits 22 through 26 (NNNNN)=5-bitoffset count of the Best Server Channel Number from the Initial PagingChannel for the serving cellular system. i.e. 00000=334 for B-Side or333 for A-Side while 10100=354 for B-Side or 313 for A-Side.

Item 2709 is known as the Extended Address word and will always occupyword position three when it is incorporated into a data message from thehandset to the pico station. This word is requested from the handset bythe pico station to allow capture of the handset electronic serialnumber for comparison with the list of allowed pico station users toprevent unauthorized system access. The handset includes word 3 in itsFull Registration message to the pico station.

FIG. 28 depicts the data message elements utilized by the pico stationin the creation of its Overhead (OHD) and Command words sent to thehandset. These words are forty bits in length as opposed to theforty-eight bit words used by the handset.

FIG. 28 items are depicted with their message position defined. Item2801 (OHD word 1), 2802 (OHD word 2) and 2804 (OHD Control Filler Word)follow the EIA-553 Standard exactly. Item 2803 (OHD word 3) has beenestablished to allow the pico station to transmit a unique identifier inthe form of a twenty-two bit base serial number to allow the handset torecognize its associated pico mode pico station during those briefperiods when the pico station is actually transmitting an overheadmessage stream.

Item 2805 (Command word 1) follows the EIA-553 Standard exactly, and isutilized by the pico station as a Single Word Command for page ofhandset and as the first word of multiple word commands issued to thehandset.

Item 2806 (Command word 2) is the second word of the two word BestServer Command issued by the pico station to the handset.

Item 2807 (Command word 2) is the second word of the two word accessacceptance message issued by the pico station to the handset when accessto the pico station is denied.

Item 2808 (Command word 2) is the second word of the two word AccessAcceptance message issued by the pico station to the handset when Accessis Accepted and the line is Idle. Local field NNN=000 through 101 as theassigned home unit number for this handset Access.

Item 2809 (Command word 2) is the second word of the two word AccessAcceptance message issued by the pico station to the handset if the LineBusy condition exists. Local Field NNN=110 if a Handset Busy conditionexists.

FIG. 29 depicts additional pico station Command words utilized incommunications with the service control unit and with the handset in thepico mode of operation.

Item 2901 (Command word 1) is the single word attention message sent tothe service control unit on the common control channel to requestservice.

Item 2902 (Command word 1) is the first word of multiple word responsemessages sent to the service control unit during configuration/updatesessions.

Item 2903 (Command word 2) is the second word of the Audit Acknowledgesent to the service control unit during Locate session.

Item 2904 (Command word 3) is the second word of the two word ACK/NAKresponse from the pico station to the service control unit duringconfiguration/update sessions.

Item 2905 (Command word 2) is the second word of the multiple wordParameter Information Transfer process executed during the handsetAuthorization function. This Command alerts the handset to the followingParameter Information commands.

Item 2906 (command word 3-N) is the Parameter Information Command wordwhich will contain the Parameter Information Identity field (PID) andthe Parameter Value field (PVAL) described in Table 1 below.

                  TABLE 1    ______________________________________    PID       PARAMETER NAME (PVAL)                                 BIT/LNGH    ______________________________________    00000001  Number of Channels to use                                 5    00000010  Transmit Power Level                                 3    00000011  ACCESS threshold RSSI                                 8    00000100  WARNING threshold RSSI                                 8    00000101  HANGUP threshold RSSI                                 8    00000110  RSSI SAMPLING interval                                 4    00000111  RSSI AVERAGING count                                 4    00001011  Base phone number NPA                                 12    00001100  Base phone number NNX                                 12    00001101  Base phone number LINE                                 16    00001110  Handset pico station count                                 2    00010001  Best Server IDENTITY                                 9    00010010  Call Forward ON command                                 16    00010011  Call Forward OFF command                                 16    00010100  Handset REGISTRATION number                                 3    00000000  END OF SESSION (11111111)    ______________________________________

FIG. 31 depicts the data message elements utilized by the servicecontrol unit in communications with the pico station. These words areforty-eight bits in length.

Item 3101 is known as the Undeniable Access Message and is sent as asingle word command.

Item 3102 is the first word of Multiple Word Command messages issued bythe service control unit to a specific pico station.

Item 3103 is the second word of the Parameter Information Commandmessage.

Item 3104 is the second word of the ACK/NAK Response message sent to thepico station upon receipt of requested data.

Item 3105 is the second word of the two word Shutdown Command whichforces the pico station to cease all pico operations and to monitor thecommon control channel for further instructions.

Item 3106 is the second word of the two word Reset Command which forcesa reset to occur in the pico station.

Item 3107 is the second word of the two word Full Audit Command whichinstructs the pico station to reply with traffic, operationalparameters, faults and diagnostic information.

Item 3108 is the second word of the two word Partial Audit Command whichinstructs the pico station to reply with traffic, faults and diagnosticinformation.

Item 3109 is the second word of the two word End Of Session Commandwhich releases the pico station from this communication session.

FIG. 30 depicts the data message formats and timing for both the Forwardchannel direction (pico station to handset) and Reverse channeldirection (handset to pico station). As shown, the data message formatsfollow exactly the EIA-553 Standard as to their transmission timedurations and their data word repetitions and order.

One difference between the Land Station protocol for cellular as definedin EIA 553, and the base station protocol involves the simultaneoustransmission of commands issued to a target handset over both the word Aand word B streams within the Forward Command Channel format, whichdisregards the normal cellular land station stream assignment which isbased on the MIN of the target handset. Cellular land stations issueseparate commands to two different handsets via the word A and word Bstreams.

Another difference with respect to the mobile station protocol forcellular versus the handset-pico mode protocol includes use of codedDigital Color Code field in the Reverse Control Channel message stream.In the pico mode, this field is set to all is during the Access attemptmessage transmission, and it is set to the target pico station assignedDigital Color Code for all other message transmissions. This is donepurposely to prevent the network cellular system from erroneouslyattempting to process this pico mode access event should signal mixingcause the message to be picked up by the cellular network.

Pico Station Configuration Process

Referring now lo the drawings, and particularly to FIGS. 7-13, theprocess steps of operation related to the pico station will be explainedin more detail. FIG. 7 represents the main idle loop of the program. Thepico station Activation function is divided into the Configurationprocess represented in FIG. 8, and an Authorization process representedin FIG. 9. Call Processing functions are illustrated in FIG. 10-13,respectively.

Obviously, as purchased, the pico station is not yet activated for useby the consumer. The Configuration function is a process to be performed"over the air" by the service control unit after the pico station islocated at the premises where it is to be used. As previously explained,a number of service control units and a host station are located in eachoverlay cell area which serves pico stations, with the host including aserver for generation of a list of service control unit locationsavailable to reach a given pico station location.

The base station Activation function involves the overhead eventsassociated with the standard customer activation system employed by thecarrier or service provider for the cellular system. In this regard, thecustomer activation process largely encompasses the process used bystandard cellular carrier systems to identify and authorize for serviceall standard cellular phones as they are activated. In addition, thepico station ESN is captured at the point of sale by the customeractivation system. The customer activation system passes this ESN to theservice control system host along with the address and telephone numberof the location where the pico station is intended for use. The customeractivation system also passes to the service control system host theMobile Identity Number (MIN) and ESN for each handset which isauthorized to use this pico station.

The control system host examines the pico station location address andselects the most likely service control units through which contactbetween the associated control unit and the targeted pico station can beaccomplished. The system host then issues a command to each selectedcontrol unit ordering the Locate task to be accomplished for the targetpico station. Each selected control unit then periodically issues, onthe common control channel, an Undeniable Access Message addressed tothe targeted pico station ESN. This message will periodically berepeated until control contact with the targeted pico station isaccomplished.

Referring now to FIG. 7, when the consumer installs the pico station atthe intended location and connects its power supply, the pico stationenters an initialization task 701. Upon power-up, the pico station'scentral processor then issues a power-on reset command and initiates atask 702 which performs certain internal housekeeping chores to placethe pico station radio and the telephone line interface of the picostation into their idle state. The pico station central processor thenuploads the contents of its EEprom in process task 702 and initiatestask 703 to determine the pico station operational status.

If the operational status check in query task 703 determines that thepico station is not yet configured, a pre-configuration task is enteredat process task 705 and the status LED is set red. During task 703, ifit is determined that operation of the pico station has been configured,then query task 704 is initiated to determine if the handsets associatedwith the pico station have been authorized.

If a No determination is reached during task 704, or a Yes determinationis reached during task 710, the pico station enters task 715 duringwhich it is tuned to the common control channel. Following task 715, aquery task 716 determines whether pico station access is required by theservice control unit.

If access is not required, the pico station proceeds to set up for thehandset Authorization process of FIG. 9. If access is required, the picostation accommodates the service control access needs as illustrated inFIG. 8.

If task 704 indicates that the handset was authorized, this means thatat least one handset has been successfully downloaded with pico modeoperating parameters during an Authorization process. A Yes result fromquery task 704 initiates query task 710 to determine if the redauthorization button on the pico station has been depressed. If thebutton is not. depressed, a query task 711 is entered to determine ifthe telephone line status has changed. If the telephone line status isnew, a task 712 is entered during which each registered handset isupdated to this event and the pico station is returned to the idle statethrough the scan channels routine. If the telephone line status isunchanged as determined by task 711, the pico station proceeds to theScan Channel process in FIG. 10.

If operation is not enabled, query task 703 initiates process task 705.Daring task 705, the pico station central processor instructs the radiopico station to alternately tune to the known A-side common controlchannel and then to the B-side common control channel to monitor whetheroverhead messages are being received from the control unit.

Query task 706 is then executed to determine if the control unit ispresent. If a negative response is indicated, a loop return is executedto the start of task 706 and the query task is repeated until thecontrol unit is found. If a positive response is identified, task 707 isentered to determine if an Undeniable Access Message from the controlunit is addressed to the selected pico station in view of the subjectESN. If not, a loop back to the beginning of task 706 is executed.

If an Undeniable Access Message from the control unit is addressed tothe target pico station, the pico station proceeds to the Configurationprocess in FIG. 8. There, the pico station then transmits, at fullpower, a Communication Set-up Acknowledge Message to the control unit.The control unit measures the received signal strength of this picostation signal and then issues an End Session Command to the picostation. The pico station then exits the Configuration process andreturns to the Main Loop entry gate 720.

Upon issuing the End Session Command to the pico station, the servicecontrol unit reports to the host the results of its Locate Command. Thehost, in turn, analyzes the results from all instructed service controlunits and selects the one receiving the strongest signal from the picostation to be the primary control for this pico station location. Thesystem host then transmits to the selected service control unit alloperating parameters that need to be forwarded to the pico station. Thisdata is encompassed within an Activation Command Sequence.

Upon receipt by the service control unit of the Activation CommandSequence, the following events are initiated. The control unit queues upa pico station Configuration session for the targeted pico station. Thecontrol unit initiates this session by first transmitting an UndeniableAccess Message addressed to the targeted pico station on the commoncontrol channel. The pico station responds with a Communication SetupAcknowledge message as represented in process task 802 of the picostation Configuration process.

Upon receipt of the pico station Communication Setup Acknowledgecommand, the control unit transmits to the pico station the parameterinformation using the standard Parameter Information Message format,after which the pico station acknowledges the receipt of the parameterinformation messages.

The rest of process task flow for the Configuration process is furtherillustrated in FIG. 8. Process task 801 proceeds to process task 802 toperform the control unit access function during which the CommunicationSetup Acknowledge is sent to the control unit. A query task 803determines whether this is the initial Configuration process performedby the pico station. If it is not, a start command timer task 804 isinitiated. If it is the initial Configuration process, a task 805 isentered to clear the EEprom ram image registers of the pico station.Following clearing of the registers, task 806 captures and acknowledgesreceipt of the best server identity. A task 807 then captures andacknowledges receipt of the power level assignment. Following task 807,a task 808 captures and acknowledges receipt of the operating channelnumbers for the pico station, and a task 809 captures and acknowledgeshandset assignments. A task 810 then captures and acknowledges operatingmode assignments and the End Session command and a task 811 saves theram image to the EEprom.

Following execution of tasks 805-811, a task 812 clears all trafficregister, in the pico station and sets the status LED to green. Uponsuccessful execution of task 812, the pico station exits back to theMain Loop process task indicated in FIG. 7.

Any NAK from the pico station will result in the transmission by theservice control unit of a retransmitted Parameter Information Message.If all messages are successful, the control unit will then issue an EndSession command to the pico station, and report the activation of thispico station to the system host. The control unit then saves to its harddisk a data file for this pico station keyed to the pico station ESN,containing the assigned parameters for the pico station.

Service control unit access events following initial configurationresult in process 804 initiating the Configuration Function Updateprocess which begins with query task 815. Query task 815 determines if acommand has been received from the control unit addressed to this picostation. A Yes result will start query task 816 which monitors commandtimer activity for expiration.

A No result at query task 816 loops back to the start of query task 815to continue monitoring for control unit commands. Expiration of thecommand timer forces a Yes result at query task 816 which returns to theMain Loop at entry gate 720.

Receipt of a command will result in a Yes at query task 815 which startsquery task 817 to detect new configuration assignments from the controlunit. A Yes result to task 817 initiates process task 818 to capture andACK the changes to pico station configuration.

Process task 818 then starts process task 819 to restart the commandtimer and then loop back to the start of query task 815 to await furthercommands.

Should the command not be a configuration change, the No result at querytask 817 starts query task 820 which determines if an End Sessioncommand has been received.

A No result at query task 820 loops back to the start of query task 815to await further commands.

When an End Session command is determined at query task 820, the Yesresult starts process task 821 to acknowledge the termination of thiscontrol unit session.

Process task 821 then starts process task 822 which saves the newconfiguration data to the EEprom, then returns to the Main Loop at 720.

The pico station, upon receipt of its initial configuration information,can then enter the Pre-authorization task and await manual depression ofthe authorization button or further contact from the service controlunit. The pico station status LED will show steady green indicating tothe customer that handset authorization may now be accomplished.

Handset Authorization Process

The consumer must then authorize each of his handsets for use with hispico station. This process is instituted to prevent unauthorized usageof the pico station and the associated telephone line. The process alsoestablishes the overall coverage area within which the pico station andhandsets will communicate. The physical location of the pico station isalso confirmed during this process, through the comparison of thecellular Best Server information collected from the handsets during theauthorization setup process with the information provided to the picostation by the service control unit during the Configuration process.

Referring now to FIGS. 7, 9, 16 and 19, the Authorization function willbe described, including both handset and pico station process tasks.

The handset to be authorized must be powered on and in the cellular idleslate indicated at task 1901. Query task 1902 will detect whether theuser is pressing the menu key. Query task 1903 then monitors for theBase Station Auth selection, made from the handset menu function, andexits to process task 1905 which will display Base Station Auth andstart the Handset Authorization task 1601. The handset must then bebrought into close proximity of the pico station, since the process taskis performed at extremely low transmit power levels, with each elementrequiring very strong signal level to prevent unintentional access toany nearby pico stations.

The consumer must then depress the authorization button on the picostation, which is detected by query task 710 in the Main Loop task 720.A Yes result from query task 710 initiates Handset Authorization task901. The pico station monitors the button On state in query task 902 andstarts the button debounce timer via task 903. Query task 904 monitorsto see that the button is still On at the debounce time-out. If thebutton is Off, a query task 904 No result causes a loop back to querytask 902, whereas the button ON test No result will cause task 901 toreturn to Main Loop 720. Debounce time is set to 500 ms to ensure theswitch has positive closure before execution of further process tasks.

If the query task 904 outcome is Yes, the pico station performs processtask 905 which tunes the pico station transmitter to the knownsetup/control channel and commences sending the authorization overheadsignal stream 3002 via the forward control channel. This overhead streamconsists of pico station words 2301, 2802 and 2803. The pico stationthen starts a ten second authorization timer in process task 906.

Referring now to FIG. 16, the execution of Handset Authorization task1601, causes entry into process task 1602, wherein the handset is tunedto the common/control channel, and a ten second authorization timer isstarted. Query task 1603 monitors for signal strength in the forwardcontrol channel of -60 dbm or more. If a pico station signal is notpresent, query task 1605 monitors for time-out of the ten secondauthorization timer. If the result of task 1605 is Yes, task 1601 exitsto cordless idle at gate 1420. Otherwise, a query task 1605 No resultcauses a return to query task 1603 to monitor signal strength again.

Once query task 1603 determines sufficient signal strength, query task1604 monitors for the presence of the pico station authorizationoverhead stream. A query task 1604 Yes result initiates query task 1605to test again for timer expiration.

A query task 1604 Yes result initiates process task 1606 which willallow the handset to commence sending its three word authorizationstream 3005 consisting of words 2701, 2707 and 2709. Word 2707 localfield will contain the I'LL TAKE IT call answer message. Thistransmission conforms to EIA-553 section 2.6.3.5 protocol for handsetreverse control channel messages.

If the pico station query task 907 does not receive a signal from thehandset at a level of -60 dbm or greater, it will not respond to thetransmission. In conjunction with that process, handset. query task 1607monitors the pico station Busy/Idle bit. in the forward control channeloverhead stream. The handset will cease the transmission upon sending of104 bits without detecting the forward control channel Busy/Idle bittransition from the pico station. A handset query task 1607 No resultpasses task 1601 to process task 1624, which will delay the task for arandom period >10 ms<200 ms. Query task 1605 is then initiated whichwill lead the handset to resend its authorization stream. The handset isprogrammed to transmit at its power level 7 (approx. 2 mw output) forthese transmissions.

The pico station query task 907 monitors the signal level of the handsetand if it is not above the minimum then query task 908 monitors forexpiration of the 10 second authorization timer. If the timer has notexpired, the pico station returns to query task 907 and retests thehandset signal level.

Should query task 908 sense that the timer has expired, the pico stationperforms process task 909 which turns off the transmitter and LED flashstate (if On) and then exits back to the Main Loop at 720. The handsetwill detect loss of signal from the pico station by query task 1603, andexpiration of its authorization timer, as detected by query task 1605,which will cause the handset to return to its Cellular Idle task throughthe Cordless Idle entry gate at 1420.

When query task 907 measures adequate signal strength from the handset,the pico station performs process task 910 during which the pico stationcaptures the handset MIN and ESN data. Query task 911 monitors thecaptured ESN and MIN against the list of allowed handsets given to thepico station by the service control unit during activation. If thehandset was not expected by the pico station, a query task 911 No resultinitiates process task 909 to terminate the authorization process. Aquery task 911 Yes result initiates process task 912, which requests andcaptures the cellular Best Server Information from the handset.

A handset query task 1607 Yes result initiates query task 1608, wherebysignal strength of the pico station is monitored for a -60 dbm orgreater level. If the pico station fails to accept the handset ESN andMIN, query task 1608 will detect the loss of signal and its No resultforces the termination of task 1601 via the cordless idle exit at 1420.A query task 1608 Yes result initiates query task 1609, which monitorsfor the Best Server command from the pico station. Failure to receivethis command will cause task 1601 to loop back to query task 1608 toagain monitor signal strength.

When query task 1609 detects the Best Server command, it initiatesprocess task 1610 which causes the handset to send the cellular BestServer information to the pico station.

Task 1610 then initiates query task 1611, which seeks to identify thecontrol filler overhead from the pico station to indicate that asuccessful link has been established for the Authorization process tocontinue. A No result at query task 1611 initiates query task 1612 whichmonitors for sufficient signal level. A Yes result at task 1612 loopsback to query task 1611. A No result at 1612 exits through the cordlessidle gate 1420.

A pico station process task 912 resulting in capture of the Best Serverdata, passes task 901 to process task 913, which will send a controlfiller word stream 2804 on the forward control channel and cause thepico station LED to start flashing. Query task 914 then compares thecaptured Best Server data against the data list of allowable cellularBest Servers downloaded to the pico station by the service control unitduring the Configuration process.

A query task 914 No result initiates process task 909 which willterminate the process if the pico station data fails to match thecellular Best Server data. This condition indicates the pico stationlocation has been changed since it was configured by the service controlunit.

Receipt of the control filler word results in a Yes at Query 1611 whichinitiates process task 1613. The handset will then commence flashing itsback-lighted display in response to process task 1613, and upon querytask 1611 detection of this initial control filler word stream, toindicate the successful start of Authorization. The handset will thenenter its parameter transfer loop. The handset light will continue toflash during the session, as long as the pico station signal remainsabove the -60 dbm level, or until the pico station issues an End Sessioncommand at session completion.

A query task 914 Yes result passes control to the pico station parametertransfer loop. This loop is used to transmit to the handset theParameter Information message 2902, utilizing the Parameter Informationmessage format described in 3001.

The pico station parameter transfer loop begins with process task 915,which starts the cycle timer. Task 901 then initiates process task 916which formats and transmits the first Parameter Information message,followed by a Control Filler word stream, on the forward control channelQuery task 917 then monitors for an ACK signal from the handset. Shouldquery task 917 result in a No result, query task 918 is initiated tomonitor whether the cycle timer is still running. A query task 918 Yesresult, initiates process task 916, thereby retransmitting the lastmessage. If query task 918 determines that the cycle timer has elapsed,the resulting No state initiates process task 909 to end the currentprocess.

A query task 917 Yes result initiates query task 919 which monitors forcompletion of the Parameter Information list. A query task 919 No resultinitiates process task 915 to pass each remaining parameter. A querytask 919 Yes result initiates process task 920 which transmits the EndSession command on the forward control channel, resulting in terminationof the LED flash, and the process then exits through 720 to the MainLoop.

The handset parameter transfer loop consists of query task 1614, whichmonitors the pico station signal strength, process task 1615 whichcaptures the Parameter Information message and issues an ACK or NAKreply on the Reverse Control Channel, and query task 1616 which monitorsfor the End Session command from the pico station. Task 1601 can exitthis loop as a result of signal loss detection during query task 1614,which then initiates process task 1622. Process task 1622 turns off thebacklight flash and returns the handset to Cellular Idle via theCordless Idle entry at gate 1420.

When query task 1616 detects the End Session command, task 1601 controlinitiates query task 1617, which compares this pico station serialnumber to the numbers of all previously authorized pico stations. A Yesresult from query task 1617 initiates process task 1623, which willdelete the previously stored information in this pico station slot.Process task 1623 then passes control to process task 1621, which willstore the parameter information collected during this authorizationinterval into the handset EEprom.

A query task 1617 No result initiates query task 1618, which monitorsfor multiple pico station authorizations for this handset. Each handsetis capable of storing information about and communicating with up tothree different pico stations. If multiple pico stations are notauthorized, a query task 1618 No result initiates process task 1623. Ayes response to query task 1618 initiates query task 1619 to determineif the authorized count of pico stations has been previously reached. Aquery task 1619 Yes result initiates process task 1622 to abort the saveprocess task. A No result from query task 1619 initiates process task1620, which increments the count of stored pico station data files andinitiates process task 1621, to save the file in the EEprom and thenreturn to Cellular Idle via the Cordless Idle entry gate at 1420.

Pico Station Main Loop

Referring back to FIG. 7, the pico station exits the Authorizationfunction through the Main Loop gate entry gate at 720. Query task 703identifies the occurrence of the service control unit activation eventand initiates query task 704, which detects the occurrence of thehandset Authorization event. A query task 704 Yes result initiates querytask 710, which monitors the state of the authorization button. A querytask 710 No result initiates query task 711, which monitors thecondition of the telephone line connected to the pico station. Shouldquery task 711 determine that the line status has changed, it initiatesprocess task 712, which will then issue update commands to allregistered handsets. A query task 711 No result passes control to theScan Channels task at gate 1001.

The pico station will spend most of its time in the Idle loop, utilizingthe telephone line interface to monitor line status and activity, andutilizing the pico station radio to scan all of its assigned channelsfor handset or service control unit access attempts.

The pico station will exit the pico station Idle loop to transmit:

a. in response to an access attempt from one of its registered handsets;

b. an Update signal to a registered handset of changes in the telephoneline status;

c. when signaling a registered handset of an incoming call;

d. when a handset is an active participant in a telephone call;

e. when the Authorization button on the pico station is depressed; and

f. in response to an Undeniable Access Message from the service controlunit.

At all other times, the pico station is in a scanning receive mode withits pico station transmitter turned off.

In order to transmit, the pico station must monitor the selected channelfor availability. i.e., freedom from transmission of other units. Thisis accomplished by measurement of Received Signal Strength Indication(RSSI), providing a numerical value that represents the amount of RFenergy present at the pico station location on the channel beingexamined. The pico station has been preset by the service control unitto a Busy Channel RSSI tolerance value above which a channel is to beconsidered to be in use by monitoring units and therefore is not to beused by the pico station for any transmission.

Handset Registration Process

Both the pico station and the handset operate in a restricted RFcoverage environment through control of transmit power and establishmentof minimum signals levels for accessing one another.

To consider a channel active for handset access attempts, the picostation has also been preset by the service control unit at an AccessMinimum RSSI level below which access attempts shall not be responded toby the pico station. Another purpose of this Access Minimum RSSI inaddition to controlling the coverage area of the pico station, is toallow the pico station to identify channels having unacceptable signallevels, and rapidly move to channels where its handsets may be trying togain access at an acceptable signal level.

The Registration process is initiated by the handset during its Rescantask when the handset location analysis process detects that it is inthe coverage area of the Best Server cell site that also covers the picostation. The handset will then periodically attempt to access the picostation by selecting an idle channel from the plurality of channels itwas given during the Authorization process task as long as the handsetremains within the Best Server coverage area. The duration of thisRegistration Attempt is sufficiently long to allow the pico station toscan through all the channels and still have time to detect the handsetRegistration Attempt and respond to the handset.

Referring now to FIGS. 10, 14, 15, and 17, the Handset Registrationprocess will be described.

The pico station enters the Scan Channels task 1001 and executes processtask 1002 which tunes the pico station receiver to the first of theplurality of channels assigned for pico station use. Control is thenpassed to query task 1003 which monitors the channel for received signalstrength above the Access Threshold level assigned to the pico stationby the service control unit during configuration. Desirably, this AccessThreshold level is set at a level higher than a warning threshold or adrop threshold. Consequently, if a user's handset is granted access,that user will have some margin for moving around without havingcommunication services being automatically dropped.

If insufficient signal level is present, a query task 1003 No resultinitiates process task 1004 which increments the channel number andtunes the receiver to the new channel. Process task 1004 then initiatesquery task 1005 which compares the current channel number with themaximum allowed channel number. If the channel number does not yetexceed the maximum number, the query task 1005 No result loops back toquery task 1003 to test signal strength on the newly selected channel.If the maximum channel number is exceeded, query task 1005 initiatesquery task 1013 which monitors the at-home timers for activity.

If no at-home timer is running, a query task 1013 No result initiatesprocess task 1018, which cancels all Handset Registrations with the picostation. Task 1010 then exits back to the Main Loop at entry 720.

The handset performs a pico Idle task in accordance with EIA-553 Rescanstandards. This task is entered at 1420 and initiates query task 1418which monitors to see if the handset is in the Home Idle mode. A querytask 1418 No result initiates query task 1401, which monitors for a picostation data fill which was acquired through the Authorization processdescribed above. A query task 1401 Yes result initiates the HandsetRegistration process at 1701.

The handset enters Handset Registration at 1701 and proceeds to utilitytask 1515 which tunes the handset to the first of the plurality ofchannels assigned for pico station use in process task 1516. Query task1517 is then initiated, which monitors the received signal strength onthat channel to determine if its less than the hang-up threshold levelprovided to the handset during the pico station authorization processdescribed above. This is the RSSI level used by the handset to determinea busy channel. If query task 1517 determines that the signal is notbelow the minimum, the No result initiates process task 1519 whichincrements the channel number and tunes the handset to this new channel.Process task 1519 then initiates query task 1520.

Query task 1520 monitors the channel number selected and compares itwith the maximum channel number allowed. If the channel number does notexceed the maximum, the query task 1520 No result initiates query task1517 to test the signal level on the newly selected channel. A querytask 1520 Yes result initiates process task 1521 to return a failure totask 1701. Query task 1702 detects the failure and initiates processtask 1707 which starts the find base station timer with a short countvalue to ensure rapid return to this process task. Control then passesback to the Rescan task at the entry gate 1402.

Once query task 1517 detects an acceptable channel, it initiates process1518 to return OK. Query task 1702 is satisfied, which initiates processtask 1703, which then starts the access timer and causes the handset tocommence transmitting the Here I Am1 message words 2701 and 2702 usingthe 3006 format. Process task 1703 then initiates query task 1704.

Query task 1704 monitors the forward control channel for signal from thepico station above the Access Threshold level. If such a signal is notpresent, the query task 1704 No result initiates query task 1705 whichmonitors the access timer running condition. A query task 1705 Yesresult initiates query task 1704 to monitor again for signal from thepico station. When query task 1705 detects access timer time-out, the Noresult initiates process task 1706.

Process task 1706 stops the transmissions from the handset and restartsthe find base station timer at its normal value. Task 1706 then returnsto the Rescan task via entry at gate 1402.

The pico station query task 1003 will answer Yes when the handset signalis sufficient and then task 1001 control initiates query task 1006 tomonitor the received signal for presence of the 10k bit Manchesterencoded data. If query task 1006 fails to detect data, the No resultinitiates process task 1004 to tune to the next channel. The Yes resultfrom 1006 initiates query task 1007, which analyzes the contents of thereceived data stream to identify a Handset Authorization Registrationmessage.

The Handset Authorization Registration message identified in task 1007may be either an initial registration, which occurs when a handset firstenters the pico system from a standard or macro cellular system, or areacquisition registration, which occurs when a handset's lastregistration was with the pico system.

A query task 1007 Yes result initiates process task 1008 which performsthe Registration process with the handset, and then exits back to theMain Loop via entry 720. The Registration process may be an extensiveregistration process which includes security checks for an initialregistration. It may be a more abbreviated process for a reacquisitionregistration. As an example, for a reacquisition task 1008 may simplyrestart the at-home timer, discussed above in connection with task 1013,associated with the handset. A query task 1007 No result initiates querytask 1009.

Query task 1009 monitors the received data message for a service controlunit Access request. A query task 1009 Yes initiates process task 1010which sets the service control unit Access Flag and starts the BaseStation Idle task at 1101. A query task 1009 No result initiates querytask 1011 which monitors the received data message for a handset Accessrequest. A Yes result from query task 1011 initiates process task 1012which sets the handset access flag and starts the Base Station Idle taskat 1101.

A query task 1011 No result loops back to process task 1004 to incrementto the next channel and continue with the scan.

Base station process task 1008 starts an at home timer at the successfulcompletion of the Registration process. This timer is a register holdingthe value of the time of the event plus 300 seconds. Query task 1013upon detecting this non-zero timer register, passes its Yes result toquery task 1014.

Query task 1014 monitors the current time value against the stored valuein each non-zero at home timer register. If the current time equals orexceeds the stored value, a query task 1014 Yes result initiates processtask 1015 which cancels the registration of the associated handset(s)for failure to reacquire the pico station within the allowable timewindow.

However, even though registration is canceled, a handset may reacquirelater without going though a full registration process. For example, thehandset may have failed to reacquire because it has been powered off. Solong as the handset resides within the same pico cell when it is againpowered on, it will attempt to reacquire, and the pico base station willaccept the reacquisition attempt. On the other hand, if the handsetfinds itself powered on outside the pico cell, it will then undergo afull registration process the next time it encounters the pico cell.

Control then initiates query task 1016 which monitors to determine ifany handsets remain registered. A query task 1016 No result returns tothe Main Loop at entry 720. A query task 1016 Yes result initiatesprocess task 1017 which performs an Update Process task for theremaining registered handset(s) to inform them of their status with thepico station. Process task 1017 then starts the Base Station Idle taskat 1101.

Base station Idle task 1101 proceeds to query task 1102 which monitorsfor ring voltage on the house line. A No result at query task 1102initiates query task 1103 which determines if the service control unitis requesting access for update or audit functions.

A Yes result at 1103 initiates process task 1105 which tunes the basestation to the common control channel and ACKs the service control unitaccess. Process 1105 initiates query task 1106 which analyzes the SCUcommand for a configuration update. A Yes result at query 1106 passescontrol to the base station configuration task at 801. A No result toquery 1106 initiates query task 1107 which determines if the servicecontrol unit command is for an audit purpose.

A No result to query 1107 exits through process task 1111 whichterminates the service control unit access and returns to the main loopat 720.

If this was an audit session, a Yes result at query task 1107 initiatesprocess 1108. Process 1108 transfers the requested audit (full orpartial) data to the service control unit and initiates query task 1109.

Query task 1109 monitors for a clear traffic register command from theservice control unit and a Yes result initiates process task 1110 toreset all traffic registers to zero.

Process task 1110 and the No result to query task 1109 both initiateprocess task 1111 to terminate the service control unit access sessionand return to the main loop at 720.

Referring again to FIG. 17, Base Station Process task 1008 causes thepico station to transmit its three word Registration Overhead messagestream (words 2801, 2802 and 2803) on the forward control channel usingformat 3002. The handset query task 1704 will detect the presence ofsignal on the channel and initiate process task 1708 which starts thedata acquisition timer. Query task 1709 then monitors the channel forthe presence of 10k bit Manchester encoded data. A query task 1709 Noresult initiates query task 1710 which monitors for data acquisitiontimer running condition. A query task 1710 Yes result loops back toquery task 1709 to monitor for data again. A query task 1710 No outputinitiates process task 1711 which causes the handset to stoptransmitting its Here I Am1 message and start the find base stationtimer with a short count value to return to this process task quickly.

A query task 1709 Yes result initiates query task 1712 which monitorsfor the pico station Registration Overhead format message. A query task1712 No result initiates process task 1717 which terminates theregistration attempt, restarts the find base station timer at its normalvalue, and returns to the Rescan task at entry gate 1402. A query task1712 Yes result starts the Process Base Overhead task at 1713.

The Process Base Overhead task then initiates query task 1714, whichcompares the received Digital Color Code in the Registration Overheadmessage against the stored Digital Color Code for this pico station. Ifthey do not match, the query task 1714 No result initiates process task1717.

A query task 1714 Yes result initiates query task 1715 which monitorsthe received System Identity against the stored SID for this picostation. A query task 1715 No result initiates process task 1717. Aquery task 1715 Yes result initiates query task 1716, which compares thereceived pico station serial number with the stored serial number forthis pico station. A query task 1716 No result initiates process task1717. A query task 1716 Yes result initiates query task 1718 whichmonitors the Busy/Idle control bit in the pico station overhead streamfor an idle condition. A query task 1718 No result also initiates querytask 1719 which monitors the number of consecutive Busy conditionsencountered against the maximum allowed count.

If the maximum count is not exceeded, a query task 1719 No resultinitiates query task 1718 to again test the Busy/Idle bit condition.Should the maximum be exceeded, the query task 1719 Yes result initiatesprocess task 1717 to terminate the registration attempt.

A query task 1718 Yes result initiates process task 1720 which causesthe handset to send its 3 word Registration message to the pico station.This message consists of words 2701, 2702 and 2709 sent in the 3005format. Process task 1720 initiates query task 1721 which monitors foran Acceptance reply from the pico station. The acceptance reply messagefrom the pico station consists of a two word combination of 2805 andeither 2808 or 2809, sent in the 3003 format.

Failure to receive acceptance causes a query task 1721 No result toinitiate process task 1717 to terminate the registration attempt. Aquery task 1721 Yes result initiates process task 1722, which capturesthe Home Handset Unit Number assignment from the pico station. Processtask 1722 then initiates process task 1723.

Process task 1723 performs the automatic Call Forward notificationfunction with the cellular switch. This function activates CallForwarding for any incoming calls directed to this handset MIN. Thesecalls will be forwarded to the pico station telephone number by thecellular switch. Process task 1723 then initiates process task 1724.

Process task 1724 sets the home flag (H-Idle=True), clears the CellularIdle flag (C-Idle=False), sets the transmit enable flag (XMIT=True) andstarts the Reacquire timer. In addition, task 1724 saves the identity ofthe pico station with which the handset is registered. This identity issaved in non-volatile memory. If this identity is not changed, thehandset will attempt to quickly reacquire the pico station afterpowering on rather than undergoing a more lengthy full registrationprocess, as discussed below. Task 1701 then loops back to the Rescantask at Cordless Idle entry gate 1420.

When a handset initially powers on, it performs a task 1400. Task 1400initializes the handset. After task 1400, a query task 1427 evaluatesthe identity of the pico station with which it was last communicating,if any. In the preferred embodiment, the pico cell identity is set tozero when the handset registers with the macro cellular system. Anon-zero code identifies a pico station. If task 1427 discovers a picocell identity of zero, program control proceeds to task 1403 todetermine the appropriate macro cellular system from which to seekcellular service.

If task 1427 discovers a non-zero pico cell identity, a task 1428 loadsinternal data tables which correspond to the identified pico station.Such data tables are loaded with the programming for SID, power levels,activated channel numbers, and the like. After task 1428, programcontrol proceeds to reacquisition gate 1801 to reacquire the identifiedpico station. By reacquiring the pico station, a full registrationprocess is omitted. By omitting a full registration process, the handsetcan rapidly be able to communicate with its pico station after beingpowered on. Thus, a user may have his or her handset powered off butlocated in one of its authorized pico cells, hear a phone ringingthrough a land-line system, power on the handset, and quickly be able toanswer the phone.

Should the handset fail to locate the pico station, the return to theRescan task is through entry gate at 1402. Control is passed to querytask 1403 which determines the appropriate system from which to seekcellular service. The System Identity assignments are specific to eitherthe non-wireline (A-Side is always Odd) or wireline (B-Side is alwaysEven) service provider.

Query task 1403 monitors the handset's stored SID for even value and theYes result initiates process task 1404. A query task 1403 No resultinitiates process task 1405.

Process task 1404 selects the B-Side setup/control channels whileprocess task 1405 selects the A-Side setup/control channels. Bothprocesses initiate task 1406, which scans the selected channels seekingcellular service in accordance with EIA-553 standards. Control theninitiates query task 1407 which monitors the result of this search forcellular service availability.

If no service is available, the query task 1407 No result initiates Busyscan entry at gate 1500 which initiates query task 1501. Query task 1501monitors for a pico station found state, and a No result initiatesprocess task 1502 which starts the find pico station timer. Process task1502 loops back to Rescan task at gate 1402 to again look for cellularservice.

If query task 1407 answers Yes, query task 1408 is initiated to monitorfor Home Idle flag=True. This test is part of the Second Line functionwhich enables a registered handset to use the cellular network tocomplete a call origination when the house line is occupied.

A query task 1408 Yes result indicates that this rescan event is asecond line attempt and process task 1409 is initiated to displayPremium on the handset.

Process task 1409 starts query task 1423 which examines the overheadglobal message for a local identity. A Yes result at query task 1423initiates process task 1424 which replaces the Premium display with theLocal display on the screen.

Process task 1424 and the No result at query task 1423 both initiatequery task 1410 which monitors the dialed digit buffer for a call to911. A Yes result at query 1410 exits to the cellular call task at theoutput number entry 1917.

If query task 1410 determines that this second line attempt was not acall to 911, the No result initiates the dial number entry process at2000.

A query task 1408 No result initiates query task 1411 which compares theSID of the available cellular system with the stored cellular SID forthis handset. If they match, a query task 1411 Yes result initiatesquery task 1412 which determines if this is the first cycle through thisloop, by checking whether the condition of the Cellular Idle Flag=True.

A query task 1412 No result initiates process task 1413 which issues theCall Forward Off command to the cellular switch to transfer calls tothis handset MIN back to this handset. Task 1413 additionally saves apico cell ID of zero in non-volatile memory. Unless this ID value isoverwritten in response to a subsequent registration with a picostation, the handset will find a pico cell ID of zero at task 1427 afterpowering up and refrain from attempting to reacquire a pico station.Process task 1413 then initiates process task 1414 which sets theCellular Idle Flag=True to ensure that only one cycle occurs throughthis loop access. Process task 1414 starts the find base station timerand initiates query task 1415. A query task 1412 Yes result or a querytask 1411 No result also initiates query task 1415.

Query task 1415 monitors the Best Server identity established during thesearch for cellular service and compares it with the stored Best Serveridentities that represent the Best Server for each of the pico stationsthat this handset is authorized to use.

The Best Server term conveys the identity of the cell site that isproviding the strongest signal to the handset from the cellular system.Each cell site is uniquely identifiable by the setup/control channelnumber it utilizes and the Digital Color Code assigned to its messagestream.

Since cellular cell sites provide coverage to a limited area, thehandset can restrict its search for one of its pico stations to thoseinstances that the handset is physically within the coverage of the BestServer cell site that is nearest to the pico station location.

It should be recognized that this technique greatly reduces the numberof unnecessary transmissions from the handset, and vastly improves theavailability of pico station channels for conversations.

Should query task 1415 identify a match of Best Servers, its Yes resultinitiates query task 1416 which monitors the find base station timer foractivity. If the find base station timer is running, a query task 1416Yes result initiates process task 1417.

Process task 1417 places the word Premium on the handset display toindicate to the user that service is being provided by the cellularsystem for which an air time charge for usage exists. Process task 1417then starts query task 1425 which monitors the contents of the overheaddata stream issuing from this cell site. Each cell site within thecellular system has a new message appended to its normal overheadstream. This is a local control message in the Global Action MessageFormat as defined in EIA-553. The 16 bit local field of this message isencoded with the zone identity of this cell site.

Each handset has a table of zone identities that was loaded during theauthorization process. Query task 1425 compares the received zoneidentity to this table and a match will result in a Yes output at query1425. The Yes result initiates process task 1426 which places the wordLocal on the display instead of Premium.

Process task 1426 and the No result from query task 1425 both return tothe cellular Idle task at 1901.

It should be recognized that the ability to display, on the handset,multiple location sensitive service availability messages greatlyenhances the customer's informed decision-making capabilities as towhat, if any, costs may incur when placing or receiving calls at a givenlocation.

Query task 1416, upon detecting that the find base station timer haselapsed, will react to the result No to start the Handset Registrationtask at 1701.

Handset Idle Mode

The home handset unit number is dynamically assigned by the pico stationand will change as handsets enter and leave the service area of the picostation.

Upon accepting the registration of a handset, the pico station starts anat-home timer for this unit. The registered handset must then reacquirethe pico station before this timer elapses or the pico station willcancel its registration.

Pico station activity in telephone calls, when uninvolved handsets areinhibited from transmitting, will suspend both the pico station'sat-home and handset reacquisition timers. Handset response to picostation OHD messages will cause the pico stations to reset theirrespective at-home timers to a value equal to the time of the event plus300 seconds.

Each handset also starts its internal reacquisition timer uponacceptance of registration by the pico station. The interval of thistimer is set to be 270 seconds, which is 30 seconds less than the picostation's at-home timer.

When the handset's reacquisition timer lapses, the handset will attemptto reacquire the pico station by locating an idle channel andtransmitting a Here I Am2 Access Attempt Registration message.

The pico station will respond to this message by repeating theregistration sequence described previously.

Each failure of the handset's to reacquire the pico station willincrement a counter. If this reacquire failure counter reaches maximumcount, the handset is forced to switch to the cellular network andattempt to acquire service there. Each successful reacquisition of thepico station by the handset resets its reacquire failure counter, andrestarts its reacquisition timer.

This process is more fully described by referring to FIGS. 14, 15 and18.

The flow from the Handset Registration task to the Rescan task at theCordless Idle entry 1420 proceeds to query task 1418 which monitors theHome Idle flag=True. A Yes result from query task 1418 initiates processtask 1419, which places the assigned home unit number on the handsetdisplay to indicate to the user that service is being provided by thepico station. Process task 1419 initiates a Monitor Base Station task atentry gate 1503.

The Monitor Base Station task initiates query task 1504 to monitor thereacquire timer for activity. If this timer has not elapsed, a querytask 1504 Yes result initiates the Monitor Base Station loop at processtask 1506. Process task 1506 then tunes the handset to the initial picostation channel and initiates query task 1507.

Query task 1507 monitors the channel for the presence of signal abovethe access threshold. If high signal is not present, a query task 1507No result initiates process task 1511 which increments the selectedchannel up by one and initiates query task 1512.

Query task 1512 monitors the handset keypad for any activity by theuser. If a key is pressed, query task 1512 starts the Cordless CallOrigination task at entry gate 2200. If no keypad activity is detected,the query task 1512 No result initiates query task 1513, which comparesthe selected channel number with the maximum channel number allowed. Ifthe channel selected is greater than the maximum, a query task 1513 Yesresult initiates query task 1504 to again test the condition of thereacquire timer. Until then, the query task 1513 No result returns toquery task 1507 to monitor the selected channel for the presence ofsignal from the pico station.

When query task 1507 detects the presence of signal, its Yes resultinitiates query task 1508 which monitors for the presence of 10K bitManchester encoded data. If the signal present is not data, a query task1508 No result initiates process task 1511 to step to the next channel.If data is present, a query task 1508 Yes result initiates query task1509.

Query task 1509 examines the data stream for pico station ordersdirected to this handset, and a Yes response will initiate the ProcessBase Order task, as defined by EIA-553 standards, at entry gate 2400. Aquery task 1509 No result initiates query task 1510 which examines thedata stream for overhead from the pico station. A Yes response fromquery task 1510 starts the Process Base overhead task at entry gate1713.

If the data stream is not the authorized pico station, a query task 1510No result initiates process task 1511 to check the next channel.

The handset will make a complete pass through all allowed pico stationchannels on the scan before returning to query task 1504 to test thereacquire timer activity.

The handset will spend most of its pico mode idle time in this scan loopmonitoring for pico station activity that may involve this handset.

When the reacquire timer expires, a query task 1504 No result initiatesutility task 1515 to find a usable channel as described previously. Theutility task Yes result returns to query 1505 which tests for channelfound. A No result loops back to query 1504 which restarts the process.

A query task 1505 Yes result starts the Reacquire Pico Station task at1801 when an idle channel is located.

The Reacquire Base Station task 1801 commences with process task 1802which starts the access timer to limit the duration of the attempt.Process task 1802 then causes the handset to begin sending the Here IAm2 Registration message stream consisting of words 2701 and 2704 in the3006 format on the reverse control channel direction of the selectedchannel.

Process task 1802 initiates query task 1803 which monitors the forwardcontrol channel direction on the selected channel for the presence ofsignal from the pico station above the Access Threshold Level. If thepico station is not responding, a query task 1803 No result initiatesquery task 1814 which monitors the access timer for activity. Should theaccess timer expire, a query task 1814 No result initiates process task1815.

Process task 1815 stops the transmission on the reverse control channeland increments the fail counter. Process task 1815 then loads theReacquire timer with a small value to ensure rapid return to this task.

Control passes then to query task 1816 which monitors the fail counterfor a value equal to the maximum number of failures allowed (three). Ifthe Reacquire pico station task failures reach the maximum count, querytask 1816 exits to process task 1817.

Process task 1817 clears the home idle flag, zeroes the reacquire timerand starts the find base station timer. This action effectively cancelsthe handset from the home condition. Process task 1817 then exits backto the Rescan task at the rescan entry gate 1402.

If the fail counter is not yet at a maximum count, a query task 1816 Noresult returns control to the Cordless Idle entry of the Rescan task at1420.

Until query task 1814 detects access timer time-out, its Yes resultinitiates query task 1803 to continue looking for pico station signal.When 1803 detects the presence of sufficient signal, its Yes resultinitiates process task 1804.

Process task 1804 starts the data presence timer and initiates querytask 1805, which monitors for presence of 10K bit Manchester encodeddata. If data is not present, a query task 1805 No result initiatesquery task 1818 which monitors the data presence timer for activity. Ifthe timer has expired, a query task 1818 No result initiates processtask 1815.

While the timer is running, a query task 1818 Yes result initiates querytask 1805 to test again for the presence of data. When data is detectedby query task 1805, its Yes result initiates query task 1806 to test thedata stream for Overhead. If the data message is not Overhead, a querytask 1806 No result initiates process task 1815.

A query task 1806 Yes result initiates query task 1807 which comparesthe received Digital Color Code in the overhead stream with the storedDigital Color Code for this pico station. If the Digital Color Code doesnot match, a query task 1807 No result initiates process task 1815. Ifthe Digital Color Codes match, query task 1807 Yes result initiatesquery task 1808.

Query task 1808 compares the received system identity with the storedSID for this pico station. If they don't match, the query task 1808 Noresult initiates process task 1815. A query task 1808 Yes resultinitiates query task 1809 which compares the received pico stationserial number with the stored serial number for this pico station. TheNo result from query task 1809 initiates process task 1815. A Yesresponse from query task 1809 initiates query task 1810.

Query task 1810 monitors the Busy/Idle bit in the forward controlchannel overhead for Idle. If the Busy/Idle bit is Busy, query task 1810No initiates query task 1819 which counts the failure and compares thecount to the maximum number of failures allowed. If the maximum has beenreached, a query task 1819 Yes result initiates process task 1815. TheNo result from query task 1819 initiates query task 1810 to test theBusy/Idle condition again.

A query task 1810 Yes result initiates process task 1811 which causesthe handset to send the three word Registration message to the picostation. This stream consists of words 2701, 2703 and 2709 sent in the3005 format on the reverse control channel. Process task 1811 initiatesquery task 1812.

Query task 1812 monitors the pico station response for acceptance ofthis registration. The pico station response consists of a two wordmessage using word 2805 with either 2808 or 2809 in the 3003 format.

If the pico station fails to accept this handset, a query task 1812 Noresult initiates process task 1817 to exit home service. A query task1812 Yes result initiates process task 1813 which performs the internalhousekeeping needed to update the handset of the pico stations status.This process task also clears the fail counters and restarts thereacquire timer. Process task 1813 then exits back to the rescan task atthe Cordless Idle entry 1420.

Cellular Idle

While the handset is away from the coverage of the pico cell, it becomesan active cellular handset. Referring to FIG. 19, operation of thehandset in the cellular idle mode process at 1901 proceeds to query task1902 which monitors for menu key activity discussed previously.

If the menu key is not pressed, the No result at query task 1902initiates query task 1906 which tests for phone key activity. A Noresults to query task 1906 initiates process task 1904 which performsnormal cellular idle functions as defined in EIA-553. Process 1904 exitsto the rescan task at cordless idle entry gate 1402.

If query task 1906 detects the phone key On, the Yes result initiatesquery task 1907 which tests for service availability. If service isunavailable, the No result at query task 1907 exits to the rescan taskat the cordless idle gate 1420.

If query task 1907 detects service, the yes result initiates the dialnumber entry task at 2000.

Handset Joining A Call In Progress

The pico station is constantly monitoring the status and condition ofthe telephone line to which it is connected. Should a call originationoccur from one of the household extensions also connected to thistelephone line, the following events occur:

a. The pico station will issue an Update message to each of itsregistered handsets. This Update message Local field will show the linestatus as In Use (word 2809);

b. Each handset will display Line In Use in place of Home # to informthe user that someone is using the house line.

The pico station will allow any of its registered handsets to join intothis call in progress. Referring to FIGS. 10, 11, 12, 13, 19, 22, and23, events are described for a handset to join the call.

When the handset user presses the off-hook (green) key in the pico mode,the event is detected by query task 1512 in the Monitor Base Stationtask which starts the Cordless Call Origination task at entry gate 2200.

The Cordless Call Origination task initiates query task 2201 whichmonitors for the green key On state. If the answer is No, query task2201 exits to process task 2202 which handles all other firstkeystrokes, then returns to the cordless idle task 1420. A query 2201Yes result initiates query 2203 to determine if the green key occurs inresponse to a ring event. A query 2203 Yes result initiates the answercall task entry gate 2120. A query task 2203 No result starts theAcquire pico station task at 2210.

The Acquire pico station task 2210 initiates the utility task at 1515 tolocate a usable channel. When query task 1515 is completed, it returnsto query task 2211.

A task 2211 No result initiates the Reorder task at 1916, which willgenerate reorder tone to the user to signify the failure to accept acall origination. Task 2211 Yes result initiates process task 2212 whichstarts the access timer and causes the handset to commence transmittingthe I Want In1 Access Request message on the reverse control channeldirection of the selected channel. This message consists of words 2701and 2706 sent in the 3006 format. Process task 2212 then initiates aContact pico station task at entry gate 2301.

The pico station will detect the handset Access request message in querytask 1011 and its Yes result initiates process task 1012, which sets thehandset access flag prior to starting the Base Station Idle task at1101.

Contact Base Station task 2301 initiates query task 2302 to monitor theforward control channel direction of the selected channel for thepresence of signal from the pico station above the access thresholdlevel. If high signal is not present, a query task 2302 No resultinitiates query task 2312 which monitors for activity on the accesstimer.

The Base Station Idle task proceeds to query task 1102 which monitorsfor ring voltage on the line. A No result from query task 1102 initiatesquery task 1103, which monitors for Service Control Unit AccessFlag=True. The No result from query task 1103 initiates query task 1104which monitors for the Handset Access Flag=True. A No response fromquery task 1104 returns to the Main Loop at entry 720. A Yes responsefrom query task 1104 initiates process task 1112.

Process task 1112 captures the handset ESN/MIN and dialed number ifready. Control then initiates query task 1113 which compares thecaptured ESNIMIN with the pico station authorized handset data. If querytask 1113 answers No, control passes back to the Main Loop at entry 720.A Yes response from query task 1113 initiates Originate or Join Calltask at entry gate 1201.

Originate or Join Call task 1201 initiates process task 1202 whichperforms an Update for all registered handsets, informing of a HandsetIn Use status, and initiates process task 1203. Process task 1203 issuesthe appropriate response message to the handset (Acceptance words 2805and 2808 if line is idle; or Voice Channel Assignment if line is inuse). The pico station awaits the handset response in process task 1203.

If the Access timer is running, a query task 2312 Yes result returns toquery task 2302 to again check for signal from the pico station. If thequery task 2312 response is No, process task 2313 is initiated, whichstops the transmission of the Access message from the handset, countsthe failure to contact the pico station and places a reduced count valuein the reacquire timer. Process task 2313, then initiates query task2314.

Query task 2314 monitors the dialed digit buffer contents for thepresence of a 911 emergency call, as entry into this process was theresult of failure to contact the pico station.

If the result is Yes, query task 2314 immediately exits the Acquire picostation task and enters the Rescan task at entry gate 1402 to attempt tolocate service from the cellular network to complete this emergencycall.

If 911 was not the dialed number, a query task 2314 No result initiatesquery task 2315 to compare the fail count with the maximum number offailures allowed. If the count is maximum, a query task 2315 Yes resultinitiates process task 2316, which cancels the handset home condition.This is accomplished by process task 2316 clearing the home idle flag,resetting the reacquire timer to zero and starting the find base stationtimer. Process task 2316 then returns to the Rescan task at the Rescanentry gate 1402.

If query task 2315 does not detect a maximum fail count, its No resultreturns to the Rescan task at the Cordless Idle entry gate 1420.

When query task 2302 detects signal from the pico station, its Yesresult initiates process task 2303 which starts the data presence timerand initiates query task 2304.

Query task 2304 monitors for the presence of 10K bit Manchester encodeddata in the forward control channel direction on the selected channel.If data is not present, a query task 2304 No result initiates query task2317 which monitors for activity of the data presence timer. A querytask 2317 Yes result initiates query task 2304 to test again for datapresence. If query task 2317 provides a No result, process task 2313 isinitiated to terminate the access attempt.

When query task 2304 detects data presence, query task 2305 is initiatedto compare the received Digital Color Code with the stored Digital ColorCode for this pico station to detect a match. If the result is No,process task 2313 is initiated to terminate the access attempt. If querytask 2305 result is Yes, query task 2306 is initiated.

Query task 2306 examines the pico station response message for a VoiceChannel Assignment Order as defined by EIA-553. If query task 2306results in a No, query task 2318 is initiated, which examines the picostation response message for acceptance in the form of words 2805 and2808.

A No response from query task 2318 initiates query task 2319, whichexamines the contents of the dialed digit buffer for the presence of911. A Yes response from query task 2319 initiates the Rescan task atthe Rescan entry 1402 to attempt to locate cellular service to handlethe emergency call. If the query task 2319 result is No, the reordertask at 1916 is initiated to inform the user of the inability to handlethe call.

A query task 2318 Yes result, or a query task 2306 Yes result initiatesprocess task 2307, which causes the handset to send its two wordresponse message to the pico station as acknowledgment. Query task 2308is then initiated which monitors for the receipt of a Voice ChannelAssignment from the pico station. A query task 2308 No result initiatesquery task 2321.

Referring now to FIG. 12, the pico station process task 1203 capturesthe handset response and initiates query task 1204, which tests thestatus of the line for Idle. A No result at query 1204 occurs when aJoin Call function is performed. This causes task 1201 to exit to seizethe house line at 1315. A Yes response from query task 1204 initiatesquery task 1205 which checks to see if the dialed number has beenreceived from the handset. A No response at query task 1205 initiatesprocess task 1208 which starts the dialing entry timer and initiatesquery task 1209. Query task 1209 monitors for dialed number capture fromthe handset. A No result from query task 1209 starts query task 1210which monitors the dialing entry timer for activity.

A query task 1210 No result forces task 1201 to exit through the updatehandset entry gate 1323. A Yes result from query task 1210 loops back toquery task 1209. A Yes result at query 1209 loops back to process task1203 to issue an ACK. A Yes result from query task 1205 starts processtask 1206 to seize the house line. Process task 1206 initiates querytask 1207 which monitors the dial out process for success. If the query1207 result is No, task 1201 exits through the Release Line entry gateat 1322.

Successful dial out will result in a Yes result from query task 1207which causes task 1201 to initiate the switch to conversation modeprocess at entry gate 1316.

Query task 2321 monitors the purpose of the access attempt as a capturepico station event with a dialed number ready to pass. A Yes response toquery task 2321 initiates process task 2323 which keeps the handset intransmitting state and passes the dialed number to the pico station forprocessing. Control then passes back to the Origination task atConversation entr 2204.

If the query task 2321 result is No, process task 2322 is initiatedwhich turns off the handset transmitter and returns to the Originationtask at Dial Number Entry 2000 to capture the dialed number from theuser.

A query task 2308 Yes result initiates process task 2309 which tunes thehandset to the assigned Voice Channel assigned (same physical channel).Query task 2310 is then initiated which monitors the pico station linestatus received for In-Use. If the result is No, that initiates querytask 2321. If the line is in use, a query task 2310 Yes result initiatesquery task 2311.

Query task 2311 monitors the contents of the dialed digit buffer for acall to 911. A Yes result initiates the Rescan task at the Rescan entry1402. A query task 2311 result No initiates process task 2320 whichkeeps the handset transmitter on and returns to the Origination task atConversation entry 2204.

Origination task conversation entry at 2204 proceeds to query task 2205which monitors the Transmit Enable Flag=True. A No response to querytask 2205 initiates process task 2208 which places the Handset In Usemessage on the display and returns control to the Rescan task at thecordless busy entry 1422. A Yes results initiates query task 2206.

Query task 2206 determines if the pico station assigned a voice channelfor this conversation. A No response to query task 2206 initiates querytask 2209 which determines if an emergency call is being placed by theuser. A Yes response from query task 2209 loops back to the Rescan taskat the Rescan entry 1402. A No response from query task 2209 exits tothe Reorder task at entry 1916 to inform the user of the failure tohandle this call.

A query task 2206 Yes result initiates process task 2207, which performsthe normal conversation function. Call completion will pass control fromprocess task 2207 back to the Rescan task at the Cordless Idle entry1420.

Once the conversation is established, pico station process task 1316initiates the hook-flash monitor loop at query task 1317 which monitorscall progress. A query task 1317 Yes result initiates query task 1318,which monitors for a hook-flash from the handset. If query task 1318response is No, that initiates query task 1319.

FIG. 32 shows a flow chart which further illustrates the processfollowed by the pico station during task 1317. As shown in FIG. 32, aquery task 3201 determines whether the call has terminated. A call maybecome terminated when a handset's user presses the On-Hook button,which causes the handset to turn off Supervisory Audio Tone (SAT) andtransmit an 1800 ms burst of signaling tone. Alternatively, the far-endof the call may disconnect from the call to return dial tone to thetelephone line. If either of these two events causes the call to becometerminated, program control exits through the "no" exit of task 1317.

If task 3201 determines that the call has not terminated, a query task3202 determines whether an interval timer has just expired. The intervaltimer is a free-running clock operated in a background mode so that itwill expire periodically. In the preferred embodiment, the intervaltimer expires once every 15 seconds. So long as the interval timer hasnot just expired, program control exits through the "yes" exit of task1317.

If task 3202 determines that the interval timer has just expired, a task3203 updates an RSSI running average. In the preferred embodiment,signal strength is averaged over the last four intervals of the intervaltimer. After task 3203, a query task 3204 evaluates this running averageto determine if signal strength has fallen below a drop, Disconnect, orHANGUP threshold. In the preferred embodiments, the drop threshold isprogrammed (see TABLE 1 above) to be a lower RSSI signal strength thanthe access threshold level. Thus, when a pico station has granted accessto a handset, a user has freedom to move around from the point whereaccess was granted without immediately being warned to do something orimmediately being dropped.

If the signal level is above the drop threshold, a task 3205 clears awarning flag, and program control exits through the "yes" exit of task1317. If task 3204 determines that the signal strength is below the dropthreshold, a task 3206 evaluates the warning flag to determine if it isset. If it is not set, program control exits through the "yes" exit oftask 1317. However, if it is set, a task 3207 is performed to drop thehandset and program control exits through the "no" exit of task 1317.

By dropping the handset, communication services cease to be provided tothe handset, and the call terminates. The handset is dropped because itssignal level has dropped to a low level that indicates it is at the edgeof the pico cell. The drop threshold is programmed to keep pico cellssmall to prevent interference with other pico cells that may be nearby.However, the handset will not be dropped unless the handset had beenwarned in the previous interval. If the handset has not been warned, itwill not be dropped, or if any previous warnings occurred in the distantpast, the handset will not be dropped.

Referring back to FIG. 13, if the query task 1318 response is Yes, thatinitiates process task 1320 which will transmit the hook-flash from thehandset to the telephone central office, and then initiate query task1319.

Query task 1319 monitors the received signal level from the handset andcompares it to the Disconnect Warning Level. A Yes response from querytask 1319 initiates process task 1321 which issues a Warning Order tothe handset. The Disconnect Warning Level is an RSSI signal strengthwhich is between the Access Level and Drop or Hangup level. In addition,task 1321 sets the above-discussed warning flag so that the handset willbe dropped during the next interval if the signal level does notimprove, as discussed above in connection with tasks 3204 and 3206. Thewarning order is issued by sending a warning message to the handsetusing voice channel control communications which are well known in thecellular telephony art. The handset responds to this warning message byannunciating the warning to the user so that the user may know to takesteps to keep from being dropped. For example, the user should generallymove closer to the base station. Process task 1321 and a No responsefrom query task 1319 each will initiate query task 1317, to continuemonitoring the call for a disconnect event.

When query task 1317 detects a Call Disconnect event, it initiatesprocess task 1322. Process task 1322 then releases the line andinitiates process task 1323 which performs an update to all registeredhandsets informing them of the existing line status and removing theHandset In Use message from their displays. Process task 1323 thenreturns control to the Main Loop at entry 720.

During this call connection, other household extensions can join orleave the call at will. The pico station will maintain this telephoneline to handset connection until one of the following Disconnect eventsoccurs:

a. The pico station fails to detect Supervisory Audio Tone from thehandset for 5 seconds;

b. The user presses the On-Hook button which causes the handset to turnoff Supervisory Audio tone and transmit a 1800 ms burst of signalingtone;

c. The far-end element disconnects from the call and dial tone returnsto the telephone line;

d. The average measured RSSI of the handset falls below the DisconnectRSSI level.

Each registered handset may receive a new unit number assignment fromthe pico station if the cause of call termination was either a. or d.above as both conditions indicate to the pico station that the activehandset is no longer in the service area of the pico station.

FIG. 33 shows a flow diagram which depicts the tasks performed in normalconversation function 2207. Task 2207 implements a normal conversationfunction for the cordless mode of operation. A similar conversationfunction is performed by a task 1915, discussed below, for the macrocellular mode of operation.

The normal conversation function performs a query task 3301 to determinewhether a voice channel control communication is being received. Thepresent invention desirably implements voice channel controlcommunications in a manner similar to that described in EIA-553. If novoice channel control communication is being received, then a query task3302 is performed to determine whether the handset is still Off-Hook. Solong as the handset is still Off-Hook, the call continues and programcontrol loops back to task 3301.

When task 3302 determines that the handset is no longer Off-Hook, thehandset's user has hung up, and the call now needs to be knocked down. Atask 3303 performs a call termination process which is consistent withEIA-553 for the situation where the handset is first party to terminatethe call. After task 3303, program control exits normal conversationfunction 2207 or 1915. The call has been completed.

Referring back to task 3301, when a voice channel control communicationis detected, a query task 3304 is performed to determine whether thecontrol communication is a release command. The release command informsthe handset that the other party has terminated the call, and a task3305 then performs a call termination process consistent with EIA-553for the handset. After task 3305, program control exits normalconversation function 2207 or 1915, and the call has been completed.

When task 3304 determines that the control communication is not arelease command, a query task 3306 determines whether the controlcommunication is a warning order, discussed above in connection withtask 1321. When a warning order is detected, a query task 3307 isperformed to cause program control to wait until supervisory audio tone(SAT) returns. As is conventional with voice channel controlcommunications, SAT is removed while such control communications takeplace but is restored after the communication is completed. When SATdisappears, the call is muted, but when SAT returns the call maycontinue. Typically the duration of muting is too brief to be noticed bya user. Program control remains at task 3307 until SAT returns.

When SAT returns, a task 3308 mutes microphone 57 (see FIG. 2) so thatno audio signals will be transmitted away from the handset. Next, a task3309 annunciates a distinctive alert to the user. In the preferredembodiment, this annunciation is in the form of an audible signal whichis played at the handset's speaker 56 (see FIG. 2). In the preferredembodiment, the audible tone is a triple beep having approximately 50 msof on time and 50 ms of off time. An audible rather than visualannunciation is used because the user typically has the handset at hisor her ear when the warning order is received and would not necessarilybe aware of a visual annunciation. Since the microphone has been muted,the warning alert is not heard by the other party to the conversation,and the flow of the conversation is less likely to be disrupted. Aftertask 3309, a task 3310 enables the microphone so that so that audio willhenceforth be transmitted to the other party in the call. After task3310, program control loops back to task 3301, and the call continues.As discussed above, the handset's user has a predetermined interval,equal to 15 seconds in the preferred embodiment, within which tostrengthen the signal received at the pico station. Typically, the userneeds to move toward the base station to accomplish this.

Referring back to task 3306, when a control communication is receivedthat is something other than a release or warning order, the handset mayperform any number of tasks to parse the control communication and thenperform a task 3311 to appropriately respond to the other controlcommunication. Typically, such other control communications are notreceived while operating in the cordless mode designated as task 2207.However, while operating in the macro cellular mode, as designated bytask 1915, the handset may receive power control commands, handoffcommands, and the like. After responding in task 3311, program controlloops back to task 3301, and the call continues.

Base Station-Handset Call Origination Process

While the pico station is in Idle mode, with the telephone lineconnected but not in use, any one of the registered handsets canoriginate a telephone call.

Conventional cellular handset dialing procedures differ dramaticallyfrom normal PSTN dialing procedures. A benefit of the present inventionderives from restoring the normal PSTN dialing procedure to the handsetof the system in both the pico and cellular modes of operation.

This has been accomplished by having the handset generate internalprecision dial tone; removing dial tone on entry of first dialed digit;analyzing the number entry against the North American Numbering Plan;and automatically releasing the number to the network upon detection ofa complete entry. Cellular customers acclimate rapidly to this system asit does not force them to learn new procedures.

Referring to FIGS. 19, 20, 21, the handset Call Origination process willbe described.

When the handset user presses the Off-Hook (green) key, events willfollow the process flow path previously described for handset joining acall in progress up to Dial Number Entry at 2000.

Dial Number Entry task at 2000 initiates query task 2001 to determine ifthis is a pico mode or cellular connection by monitoring the Home IdleFlag=True condition. A No result from query task 2001 initiates processtask 2005. A Yes result from query task 2001 starts query task 2003which monitors for Transmit Flag=True. The No result from task 2003initiates process task 2004 which places the Handset In Use message onthe display and returns to the Rescan task at the Cordless Busy entry1422.

Cordless Busy Entry 1422 initiates query task 1421 as part of the secondline option process. Query task 1421 monitors for the green off-hook keypress and a Yes result will loop back to the Rescan task at query 1403as previously described. A No result at query task 1421 starts themonitor base station at entry 1503.

If the transmission flag was true, a Yes result at query task 2003initiates process task 2005 to clear the digit collection buffer, resetthe digit counter to zero and to set the maximum expected digit count atseven. Control then passes from 2005 to process task 2006.

Process task 2006 turns on the internal precision dial tone generator toindicate to the user that a call may be placed. Process task 2006 theninitiates query task 2008 at the Digit Capture entry gate 2007. Querytask 2008 monitors for any key being depressed.

A query task 2008 No result initiates query task 2009 which monitors forservice available, by examining the signal being transmitted by the picostation on the selected channel and comparing its level to thedisconnect level if H-Idle is true, or checking for macro cellularservice if C-Idle is true. If query task 2009 fails to identify presenceof service, its No result initiates process task 2013, which removes thedial tone and exits back to the Cordless Idle task at entry gate 1420.

With service available, a query task 2009 Yes result initiates querytask 2021 which tests the Home Idle=True Conditions. A No result fromquery 2021 initiates query task 2011. A Yes result from query 2021starts query task 2010 which monitors the Transmit=True flag. If thequery 2010 result is No, the Dial Number Entry task exits through thebusy exit gate at 2021. A Yes result from query task 2010 also startsquery task 2011 which checks the entry timer activity.

A query task 2011 No result indicates that the user has failed to makean expected entry. This starts query task 2012 which monitors for digitbuffer empty state. If some number of digits have been collected, aquery task 2012 No result initiates the Speed Dial task at entry gate1908.

An empty buffer allows query task 2012 Yes to pass control back to thedigit collection loop at the process task 2005 which restarts theprocess. A query task 2011 Yes result initiates task 2008.

When task 2008 detects a key press, the Yes result initiates query task2014 which tests the Home Idle=True Condition. A No result from 2014initiates query task 2016. A Yes result from query task 2014 startsquery task 2015, which checks whether a second Off-Hook (green) key waspressed within two seconds of the initial Off-Hook that started thecall. That procedure is used by the handset to bypass the pico stationpico mode. This is the second line function which allows the user toforce his call origination to the cellular system. One reason for makingthis choice would be a Line Busy condition on the house line with animportant call to make. Yes response from query task 2015, causing exitfrom the origination task and entry of the Rescan task at gate entry1402.

A No response from query task 2015 initiates query task 2016 whichexamines the key pressed to see if the key was numeric. A No responsefrom query task 2016 initiates the Non-Numeric Entry task at entry gate2102. The Non-Numeric Entry task at 2102 proceeds to query task 2109which monitors for a Clear key press. If the task 2109 response is Yes,that initiates query task 2110 which checks the digit buffer for emptycondition. If the buffer is empty, a query task 2110 Yes resultinitiates the Dial Number entry task at the beginning entry 2000. Thisaction leaves the dial tone on.

If the dial digit buffer is not empty, a query task 2110 No responseinitiates process task 2111 which deletes the last digit entry from thedigit buffer and reduces the digit counter by one. Control is thenpassed to query task 2112 to check the digit buffer for empty conditionafter this removal. A No response from task 2112 initiates the digitcollection loop at the Digit Capture entry 2007. Should task 2112 findthe digit buffer empty, its Yes result will restart the Dial NumberEntry task at 2000, which will then restore the dial tone to the user.

If query task 2109 response is No, that initiates query task 2113 whichmonitors the first key pressed for the (#) key. That key acts as thehandset Redial Last Number key. A Yes response from query task 2113initiates process task 2114 which retrieves the Last Number Called andplaces it into the digit buffer. Process task 2114 initiates query task2115 which monitors the digit buffer for empty.

If the query task 2115 response is Yes, that causes a loop back to thestart of the Dial Number entry task at 2000. If the query task 2114response is No, that initiates process task 2116 which removes the dialtone and initiates the Dial Complete task at entry gate 2020.

If the first entry was not a (#) key, a No response at query 2113initiates query task 2118 which monitors the first key pressed for the(*) key. A Yes response from 2118 initiates process task 2119 whichremoves dial tone and initiates the process task 2120. Process task 2120saves the (*) in the digit buffer and initiates process task 2107 whichstarts the Interdigit timer running. Process task 2107 returns controlto the digit collection loop at the digit capture entry gate 2007.

If the first entry was not an (*), a No response from query task 2118initiates process task 2121 which generates a burst of Error Tone to theuser and then initiates process task 2107 to start the interdigit timer.

Referring back to FIG. 20, if the key pressed was numeric, a query task2016 Yes result initiates process task 2017, which saves the digit inthe digit buffer, and increments the digit counter by one. Control thenpasses from task 2017 to query task 2018 which compares the digitcounter output against the maximum digit count. A Yes response fromquery task 2018 initiates query task 2019 which will direct theoriginate task-to the appropriate service by monitoring the HomeIdle=True condition. A No result from query task 2019 passes control tothe output number task at entry gate 1917 and the call will be handledon the cellular network. A Yes result at query task 2019 initiates theCapture Base Station task at 2213.

If all expected digits have not yet been entered, a No response fromquery task 2018 initiates the Numeric Entry task at 2101 of FIG. 21. TheNumeric Entry task proceeds to query task 2103 which monitors for thefirst dialed digit. A Yes response from query task 2103 initiatesprocess task 2104 which removes the dial tone signal and then initiatesquery task 2105, which monitors this first digit for either a 1 or a 0indicating a toll call is being placed. A task 2105 Yes responseinitiates process task 2106 which resets the digit count maximum valueto 11. A No result at query 2103 and a No result from task 2105 eachinitiate query task 2108.

Query task 2108 compares the accumulated digits in the digit buffer withthe North American Dialing Plan to detect a dial complete status. A Yesresponse from query task 2108 initiates the Dial Complete task at 2020.A task 2108 No response initiates process task 2107 which restarts theinterdigit timer.

This unique dialing plan for the handset which utilizes a digit counterprocess task, interdigit timer process task and comparison to the NANPstandards coupled with internal precision dial tone generation enablesthe user to rapidly enter the desired dialed number. This, in turn,brings to cellular and other special handset usage the advantages ofdial tone and the ease of familiar dialing protocol, without send andend button function.

Speed dialing is also internally supported by the handset throughinterdigit time-out with a non-empty digit buffer by control passing tothe Speed Dial entry at gate 1908 from query task 2012 in Digit Capturetask 2007. Control proceeds to query task 1909 which monitors the digitcounter for a value less than or equal to three which allows for up to200 speed dial storage registers. A No response from query task 1909initiates the Dial Complete task entry at 2020. A Yes response fromquery task 1909 initiates query task 1910.

Query task 1910 monitors whether the value in the digit buffer fallsbetween 1 and 199 speed dial register values. A No response from querytask 1910 initiates Dial Complete task entry at 2020, while a Yesresponse initiates process task 1911 to recall the contents stored atthe selected memory location, and places them into the digit buffer.Process task 1911 then initiates query task 1912.

Query task 1912 monitors the digit buffer for empty condition. A Yesresponse to task 1912 will cause return to the start of Dial NumberEntry task 2000. A No response from query task 1912 initiates the DialComplete task entry at gate 2020, to place the call.

Dial Complete task at 2020 proceeds to query task 2019 to determinerouting as described previously.

The cellular origination process of Output Number at entry gate 1917initiates process task 1913 which originates a call to the cellularnetwork with the accumulated number as the destination address. Processtask 1913 then initiates query task 1914 at the cellular conversationentry point 1918.

Query task 1914 monitors for receipt for a voice channel assignment fromthe cellular switch. Should the call fail to complete, a No result fromquery task 1914 initiates process task 1916 which generates a reordertone to alert the user that the call did not go through. Control thenpasses from process task 1916 back to the Rescan task at the idle entrygate 1420.

If the query task 1914 result is Yes, control passes to the normalcellular conversation function at task 1915. Upon call completion,process task 1915 returns control to the Rescan task at the CordlessIdle entry gate 1420. Normal cellular conversation function task 1915 isdescribed in more detail above in connection with FIG. 33.

The Capture pico station entry at 2213 of FIG. 22 initiates process task2214 which turns on the handset transmitter and begins sending the IWant In2 Access Demand message to the pico station on the selectedchannel. Control then passes from process task 2214 to the contact picostation task 2301 discussed above.

Referring again to FIG. 12, the pico station detects the Access Demandmessage and captures the dialed number from the handset. As previouslydescribed, process task 1203 issues the Voice Channel response andcaptures the handset acknowledgment. Process task 1203 initiates querytask 1204, which monitors the house line Idle state.

A Yes response from query task 1204 initiates query task 1205 whichmonitors for dialed number capture. A Yes response from task 1205initiates process task 1206. Process task 1206 seizes the house line andinitiates query task 1207 which detects dial tone and outdials thenumber captured from the handset into the network. Failure to completethe dialing process task initiates process task 1322 to terminate thecall.

Successful completion of query task 1207 initiates the Switch toConversation process task at 1316 which will switch to the conversationmode as described in EIA-553 standards. Control passes to the hook flashmonitor loop as previously described.

During this call connection process, other household extensions can joinor leave the call at will. The pico station will maintain this telephoneline to handset connection until one of the disconnect events occurs.

Each of the registered handsets may receive a new unit number assignmentfrom the pico station if the call termination occurred since the activehandset was no longer present in the service area of the pico station.

Base Station Handset Call Termination Process

While in the pico station Idle task, the telephone line interface willalert the pico station to an incoming call by detecting the presence ofring voltage on the line. The pico station then immediately initiatesthe Call Termination process.

Referring to FIGS. 9, 11, 13, and 24 the Call Termination process willbe described.

As described previously, the pico station Scan Channels task will startthe Base Station Idle task at entry 901 after processing active at-hometimers. The pico station is not involved in call activities unless ahandset is Home.

The Base Station Idle task proceeds from entry 1101 to query task 1102which monitors for ring voltage on the house line. A Yes response fromquery task 1102 initiates the Terminating Call process at 1300.

Control passes to process task 1301 which starts the ring return timerwith an interval of five seconds. The North American Telephone Systemutilizes a ring cycle of two seconds On and four seconds Off.

Process task 1301 initiates process task 1302 which locates an Idle picostation channel and issues a Page Order to each authorized handset. Thisactivity includes the collection of responses from the handsets to thePage Order. This process task follows the EIA-553 standard for messageconfigurations.

The handset Monitor Base Station task will detect the pico station PageOrder during query task 1509, and will start the Process Base Order taskat 2401. The Process Base Order task entry at 2401 initiates query task2402 which compares the type of order with Page Order. A Yes responsefrom query task 2402 initiates query task 2403.

Query task 2403 monitors the pico station Busy/Idle bit for Idle. A Noresponse from query task 2403 initiates query task 2405, which countsthe failures and compares the fail count to the maximum fail countallowed. A Yes response from task 2405 causes exit of the Process BaseOrder task and initiates the Rescan task at Cordless Idle entry 1420.

A No response from query task 2405 initiates query task 2403 to againtest the Busy/Idle bit state. A Yes response from query task 2403initiates process task 2404 which issues an Acknowledge signal to thepico station. Process task 2404 then initiates the Rescan task atCordless Idle entry 1420.

Base station process task 1302 then initiates query task 1303 whichmonitors for any responses from the paged handsets. A No answer fromquery task 1303 loops back to Base Station Idle task at 1101 which theninitiates the process task again. A Yes response from query task 1303initiates process task 1304.

Process task 1304 will issue an Alert On Order to each of the handsetsthat ACK'D the Page Order.

The handset will capture the order in the Monitor Base Station task atquery task 1509 and restart the Process Base Order task at entry 2400.Again, control initiates query task 2402 which monitors for a PageOrder. The No response from query task 2402 initiates query task 2406which monitors for the Alert Orders. A Yes response from query task 2406initiates query task 2407, which monitors for Alert On Order. A Yesresponse from query task 2407 initiates process task 2408 whichactivates the internal ringer in the handset to alert the user of theincoming call. Process task 2408 then initiates the Rescan task atcordless idle entry 1420.

The pico station process task 1304 then initiates query task 1305, whichmonitors for answer from a household extension. A Yes response fromquery task 1305 initiates process task 1311 which issues a Release Orderto each handset that was alerted.

Process task 1311 then issues an Update Order to inform the handsets ofthe Line In Use status. Control then returns to Base Station Idle taskat entry 1101.

A No response from query task 1305 initiates query task 1306 whichmonitors for answer from a handset. The No result from query task 1306initiates query task 1307 whereby the line Ring condition is againtested. A Yes response to query task 1307 initiates process task 1308which restarts the Ring Return timer for another five second interval.Process task 1308 and a No result from query task 1307, each initiatequery task 1309.

Query task 1309 monitors for Acknowledge receipt from all handsets. A Noresponse to query task 1309 initiates process task 1312 which issues aPage Order to each of the non-responding handsets. Process task 1312initiates process task 1313 which issues an Alert On Order to each ofthe responding handsets. Process task 1313 and the Yes result from querytask 1309 each initiate query task 1310.

Query task 1310 monitors the ring return timer for activity. If thetimer has expired, the system determines that the caller has hung-up.Consequently, a Yes response to query task 1310 initiates task 1311 toterminate the call. A No response from query task 1310 loops back toquery task 1305 to test for answer from the house extensions again.

Referring now to FIG. 24, the Process Base Order query task 2406 Noresult initiates query task 2410, which monitors for a Release Orderfrom the pico station. A Yes response to query task 2410 initiatesprocess task 2411 which turns off the alert ringer, returns thedisconnect response and initiates the Rescan task at Cordless Idle entry1420.

A No response from query task 2410 initiates query task 2412 whichmonitors for Update Order from the pico station. A Yes response fromquery task 2412 initiates process task 2413 which captures the newstatus and initiates query task 2414. A No result from query task 2412loops back to the Rescan task at the Cordless Idle entry 1420.

Query task 2414 monitors the Busy/Idle state of the pico station forIdle. A No response from query task 2414 initiates query task 2421 whichcounts the failure and compares the accumulated count against themaximum failure count allowed. A Yes result from query task 2421 loopsback to the Rescan task at Cordless Idle entry 1420. A No response fromquery task 2421 loops back to query task 2414 to again test theBusy/Idle state.

A Yes result at query task 2414 initiates process task 2415 whichacknowledges the update and initiates query task 2416. Query task 2416monitors the Update Order for a Handset In Use message. A No result atquery task 2416 initiates query task 2422. Task 2422 monitors the UpdateOrder for a Line In-Use message. A No result at query task 2422initiates query task 2423. Task 2423 monitors the Update Order for anIdle message. A No response to query task 2423 loops back to the Rescantask at Cordless Idle entry 1420.

When the user wishes to answer an incoming call the Off-Hook key ispressed. This action is detected by the Monitor pico station function ofquery task 1512 and the No result starts the Call Origination task atentry 2200.

As previously explained, origination task entry 2200 initiates querytask 2201 which monitors for the Off-Hook (green) key pressed condition.A Yes response to query task 2201 initiates query task 2203 whichmonitors for Alert Ringer On state. A Yes response from query task 2203starts the Answer Call task at entry 2122.

Referring now to FIG. 21, the Answer Call task entry 2122 initiatesquery task 2123 which monitors the Busy/Idle state of the pico station.A No response from query task 2123 initiates query task 2129 whichcounts the failure and compares the accumulated count to the maximumallowed failure count. A Yes result from query task 2129 returns to theRescan task at Cordless Idle entry 1420. A No response from query task2129 initiates query task 2123 to again test the Busy/Idle state.

A Yes response from query task 2123 initiates process task 2124 whichsends the I'll Take It message to the pico station. Process task 2124initiates query task 2125 which monitors for an acknowledge from thepico station.

Referring now to FIG. 13, the pico station detects the answer from thehandset in query task 1306 which initiates process task 1314. Processtask 1314 issues an Alert Off Order to all other handsets, acknowledgesthe I'll Take It message from the answering handset and issues an UpdateOrder to all other handsets. The update order is a message thatinstructs the handsets to display "Handset In Use," or the equivalent.In this mode, all other handsets are denied services through the picosystem. However, communication services may still be available throughthe macro cellular system. Process task 1314 then initiates process task1315 which seizes the line to answer the call and initiates process task1316 to commence the conversation via a process which has been describedpreviously.

Referring back to FIG. 24, the Alert Off Order is captured by thehandsets in query task 2407 which then initiates process task 2409 toturn off the alert ringer. Process task 2409 initiates the Rescan taskat Cordless Idle entry 1420.

The answering handset remains in a tight loop at query task 2125 of FIG.21, awaiting pico station ACK. A No result from query task 2125initiates query task 2126 which monitors for an Update Order directed tothis handset. Should another handset contend for answer and succeed, ayes response from query task 2126 will initiate the Process Base Ordertask at entry 2401.

A No response from query task 2126 initiates query task 2127 whichmonitors the pico station signal strength for greater than thedisconnect level. A Yes response from query task 2127 closes the loopand initiates query task 2125 awaiting the pico station ACK. A loss ofpico station signal will force a No response from query task 2127 andinitiate process task 2128, which clears the display and cancels thealert ringer. Process task 2128 loops back to the Rescan task at theRescan entry 1402.

Receipt of the pico station ACK at query task 2125 initiates theOrigination task at the Cordless Conversation entry 2204 previouslydescribed.

Each non-answering handset receives an Update Order. Referring now toFIG. 24, the Process Base Order query task 2416 detects the status asHandset In Use and the Yes result from query task 2416 initiates processtask 2417. Process task 2417 places the Handset In Use message on thedisplay and initiates query task 2418 which monitors for a new commandfrom the pico station. Likewise, a Yes response from query task 2422initiates a process task 2424, which places the Line In Use message onthe display. A Yes response from query task 2423 initiates a processtask 2425 which places the Idle message on the display. After either oftasks 2424 or 2425, program control proceeds to task 2418 to monitor fora new command from the pico station.

The No result from query task 2418 initiates query task 2419 whichmonitors whether the pico station signal strength is above thedisconnect level. A Yes response from query task 2419 loops back toquery task 2418 to test for a pico station order. All handsets will stayon this channel for the duration of the active handset's involvement inthe call.

Should a handset from query task 2419 lose signal from the pico stationthe No result initiates process task 2420 which clears the display andreturns control to the Rescan task at entry 1402.

Receipt of a new order from the pico station will force a Yes responsefrom query task 2418 which initiates the Process Base Order task atentry 2401.

This sequence completes the call process flows for the handset and picostation.

Alternate Line Option Module

The alternate line option module consists of a modified cellulartelephone housed in an exterior mountable enclosure powered from an acsource with internal battery backup. The modifications to this cellulartelephone unit include the addition of a switchable PSTN telephone lineinterface, additions to permit Remote Programming System compatibility,and other custom operating software.

The purpose of the alternate line option is to provide flexible accessprovisions for call traffic allocation. This function can be limited tothe Inter-exchange carrier (IXC) or can extend to the local exchangecarrier (LEC) as well. The function is referred to as competitive accessprovision herein.

The alternate line option is an independent device in that it can bedeployed with or without a pico station or dual mode handsets. Thealternate line option acts as an rf link to the customer site, whichprovides alternative access to the PSTN by means of the local cellularcarrier.

The alternate line option module operates under the control of the localcellular carrier. It monitors the calls originated from the house andselectively routes calls to the cellular system for completion. Thealternate line option also monitors the macro cellular network and iscapable of routing calls placed to the alternate line option's MIN ontothe house wiring for completion. The selection process, linesubstitution function and mode of operation are downloaded to thealternate line option from the cellular carrier via the remoteprogramming capability previously described. The use of the remoteprogramming line ensures positive control of the alternate line optionmodule by the cellular carrier.

In the embodiment illustrated, the PSTN central office line to the houseterminates at the input of a standard network interface device (NID)provided by the local exchange carrier. The output of the interfacemodule connects to the house wiring. The house wiring connects all ofthe customer's telephone equipment (extensions, FAX machines, computermodems, cordless telephones, etc.) to the central office line. Thealternate line option module is installed by connecting its input to theoutput of the NID. The house wiring is then connected to the output ofthe alternate line module. This places the alternate line option inseries with the house wiring.

This method of interconnection allows the alternate line option moduleto become a central office substitute during those periods when thealternate line option is actively providing the competitive access tothe household from the cellular carrier.

Referring now to FIG. 25, the initialization functions and remoteprogramming operation of the alternate line option module will bedescribed.

Upon application of power, task 2501 is started which will performinternal housekeeping chores to place the telephone line interface andthe cellular radio unit into their idle modes. The alternate line optionmodule is designed to ensure that its line interface and radio unit fail(fault or loss of power) in an On-Hook state and transmitter offcondition, respectively.

Task 2501 passes control to process task 2502 which will upload thecontents of the non-volatile memory to determine operational status.Process task 2502 then initiates query task 2503 which tests for aprogrammed MIN.

If the MIN is not yet programmed, the alternate line option module willattempt to place a cellular call to the host at a factory programmed1-800 number until contact with the host is established.

This attempt will be made on the strongest cellular carrier accesschannel serving the alternate line option module initially (A-side orB-side). If the call is not accepted by the carrier for completion, thealternate line option module will switch sides and attempt the callagain. If the host is busy and cannot process the alternate line optioncall, the alternate line option module will retry at five minuteintervals until connection is established.

A No result from query task 2503 initiates to process task 2509 whichwill start the status led flashing red as an indication that thealternate line option is inoperative. Process task 2509 then selects theB-Side system and initiates control to query task 2510 which monitorsavailable cellular service.

A Yes result from query task 2510 initiates process task 2512 whichoriginates a call to the 1-800 number assigned to the host. Query task2513 is then initiated to determine if the call was accepted by theselected system. The cellular carrier deploying the alternate lineoption module will program his switch to accept calls to the remoteprogramming number without requiring the calling unit to have a validMIN. If the query task 2513 result is No, or with a No result from querytask 2510, process task 2511 is initiated which forces the alternateline option module to switch to the other cellular system.

Process task 2511 then loops back to query task 2510 to test foravailable service again. A Yes result from query task 2513 starts querytask 2514 which determines if the host accepted the call from thealternate line option module.

If the host failed to answer, a query task 2514 No initiates processtask 2534 which enters a five minute delay before looping back to querytask 2510 to attempt again to contact the host.

A Yes result from query task 2514 initiates process task 2515 whichobtains a download from the host that contains the alternate lineoption's MIN, SID, current date/time setting for the Real-Time clock,host Check-in date/time window and Mode of Operation Parameters.

The Mode of Operation Parameters for the alternate line option moduleinclude the local exchange alternative (LEC bypass) directives andinter-exchange alternative (IXC bypass) directives. These parameters arestored in the central processing non-volatile memory.

Process task 2515 then connects to query task 2516 which monitors for acompleted host download. If the download process failed, the query task2516 No result will initiate process task 2534, to perform a delay andtry again.

A Yes result at query task 2516 starts process task 2517 which restoresthe status LED to a steady green condition to indicate the alternateline option module is now programmed and operational. The status LED isprovided as a service tool to aid in malfunction diagnostics should theneed arise.

Process task 2517 exits to the primary service loop of the alternateline option, the Check Window entry at 2505.

At any power on reset event which follows the remote programming systemdownload, a Yes result from query task 2503 will initiate query task2504 which tests whether the internal real time clock is functioningnormally. A Yes result at query task 2504 exits to the primary serviceloop entry Check Window at 2505.

A No result from query task 2504 initiates an immediate process tocontact remote programming system for the correct Time of Day. This isaccomplished by starting query task 2524 which tests for cellularservice availability. If service is available, the Yes result from querytask 2524 starts process task 2525 which originates a call to the host.Process task 2525 initiates query task 2526 which monitors the answerfrom the host. A No result from query task 2526 initiates process task2529 which creates a one minute delay and then loops back to processtask 2525 to try again.

An answer from the host provides a Yes result from query task 2526,which starts process task 2527. Process task 2527 obtains a real timeclock update from the remote programming system. Control then passes toquery task 2528 to determine load success. A No result at query task2528 loops back to process task 2529. A Yes result to query task 2528exits to the primary service loop at 2505, the Check Window entry.

Should query task 2524 determine that no service was available, its Noresult initiates process task 2535 which will light the status LED asteady red, and log the alarm condition into the non-volatile memory toallow reporting the event to remote programming system. Process task2535 then starts query task 2536 which will continue to monitor forcellular service availability.

Query task 2536 remains in a tight loop if service is not available byhaving its No result loop back to the start of query task 2536. A Yesresult from query task 2536 initiates process task 2537 which restoresthe status led to a steady green and loops back to process task 2525 toattempt to contact the host.

The Check Window task entry at 2505, as previously described in severalprocess steps, initiates query task 2506 which follows standard cellularprotocol, to determine if cellular service is available at the alternateline option location which matches the SID of the cellular carrierdownloaded from the host.

A No result from query task 2506 connects to process task 2530 whichlights the status led a steady red to indicate the alarm condition andlogs the event into the non-volatile memory to report it later to thehost. Process task 2530 initiates query task 2531 which remains in atight loop monitoring for service availability. A query task 2531 Noresult loops back to the start of query task 2531. Once service isavailable, the Yes result from query task 2531 starts process task 2532which restores the status LED to a steady green state and returns to theCheck Window task entry at 2505.

With service available, a Yes output to query task 2506 initiates querytask 2507. The alternate line option module maintains a real-time clockand calendar to determine when its operating window is enabled and whenit should contact the host for possible update to its operatingparameters. Query task 2507 tests the current date/time against thestored remote programming call in window. If the call-in window is open,the Yes result to query task 2507 starts query task 2533.

Query task 2533 determines the delay timer activity, and a No result toquery task 2533 initiates query task 2518 which monitors for serviceavailability. A No result from query task 2518 loops back to the CheckWindow entry at 2505.

A Yes result to query task 2518 starts process task 2519 whichoriginates a call to the host. Process task 2519 initiates query task2520 which tests for an answer from the host. Should query task 2520fail to determine Remote programming system answer, a No exit will startprocess task 2523 which starts the delay timer with a 30 second time-outvalue. Process task 2523 then loops back to the Check Window entry at2505.

If the answer from the host produces a Yes result at query task 2520, itstarts process task 2521 to obtain an update from the host. Process task2521 initiates query task 2522 to determine successful completion of theupdate.

A No result from query task 2522 initiates the delay timer process taskat 2523 while a Yes result loops back to the Check Window entry at 2505.

If the host call in window is closed, the query task 2507 No resultinitiates query task 2508. A Yes result to query task 2533 alsoinitiates query task 2508. Query task 2508 compares the currentdate/time against the value downloaded from the remote programmingsystem to determine if the alternate line option module service windowis open. The existence of this service window allows the cellularcarrier to exercise traffic management during periods when the cellularsystem may have limited capacity to handle household call traffic.

If query task 2508 determines the service window to be closed, the Noresult loops back to the Check Window entry at 2505. If the servicewindow is open, the Yes result to query task 2508 starts the alternateline option On Line task at entry gate 2601.

Therefore, when the service window is closed or the alternate lineoption is not receiving service from the cellular system, the alternateline option module will ignore all line activity in the household.

Referring now to FIG. 26, the alternate line option service functionswill be described in more detail. When the operating window is enabled,and the alternate line option radio unit is receiving service from thecellular system. The alternate line option On Line task is entered at2601 which initiates query task 2602 to monitor the line current todetermine Off-Hook indication. A Yes result to query task 2602 initiatesquery task 2603 which tests the real time clock for the start of a newminute.

To ensure coverage of all time sensitive events, query task 2603 willexit the alternate line option On Line task and return to the CheckWindow entry at 2505 on the start of each new minute if the alternateline option On Line task should discover the line to be in use at thestart of its service window. A No result at query task 2603 loops backto the start of query task 2602 to continue monitoring the line status.

When the line is Idle, the No result to query task 2602 initiates querytask 2604 which monitors the alternate line option configuration data todetermine local exchange company bypass mode activity. A Yes result toquery task 2604 starts process task 2605 which activates the linetransfer mechanism.

Process task 2605 acts to disconnect the house wiring from the centraloffice and substitutes the alternate line option module functions forall central office functions. Process task 2605 and the No result fromquery task 2604 both start query task 2606.

Query task 2606 monitors the house line to determine if an extension isOff-Hook. A Yes result to query task 2606 starts query task 2622 whichmonitors for the LEC bypass mode. A Yes result to query task 2622initiates process task 2623 to generate precision dial tone to the houseline.

Process task 2623 and the No result to query task 2622 start processtask 2624 which captures the first dialed digit and passes control toquery task 2625.

Query 2625 determines LEC bypass mode activity and a Yes resultinitiates process task 2626 to remove the dial tone signal. Process task2626 and the No result from query task 2625 initiate query task 2627which determines if this first digit is either a one or zero. Eithercase results in an access review.

Should query task 2627 produce a No result, query task 2628 is startedwhich monitors for LEC bypass mode activity. If the alternate lineoption is in the IXC bypass mode, a No result from query task 2628initiates process task 2629 which captures the dialed exchange code(first three digits). Process Task 2629 then initiates query task 2630which determines if this exchange code (NNX) is a member of the list ofexchanges to be diverted to the cellular carrier for completion. A Noresult at query task 2630 returns to the Check Window entry gate 2505.

A Yes result at query task 2630 and the Yes result at query task 2628start process task 2631 which captures the complete dialed number.Process task 2631 then initiates query task 2632 which tests for LECbypass mode. A No result to query task 2632 starts process task 2633which seizes the line away from the central office and effectively dropsthe call to the PSTN. The house connection is now to the alternate lineoption module output interface which keeps the line supplied with -48vdc talk battery. Process task 2633 and a Yes result to query task 2632initiate process task 2634 which originates a cellular call to thecollected dialed number.

Process task 2634 connects the house line audio circuit so the callercan hear the line supervision provided in response to this callorigination. Process task 2634 then starts query task 2635 whichmonitors the call event for activity. Control remains at query task 2635until a call disconnect event, by looping the query task 2635 Yes resultback to the start of query task 2635. Occurrence of a disconnect eventproduces a No result to query task 2635 which initiates process task2636.

Process task 2636 drops the alternate line option originated call andreleases the house line if it was seized. The alternate line option onLine task then returns to the Check Window entry gate 2505. A calldiverted by the alternate line option module will be completed beforethe alternate line option window can close.

Should query task 2606 result in a No result with respect to extensionactivity, query task 2607 is started which monitors for the receipt ofan inbound call directed to the alternate line option MIN from thecellular carrier. A Yes result to query task 2607 initiates query task2608 which determines if alternate line option MIN calls are IXC bypassevents which should pass to the house line.

If the query task 2608 result is No, process task 2609 is started whichanswers the alternate line option MIN call and responds to the hostAccess protocol. Process task 2609 initiates query task 2610 whichdetermines if the remote programming system is the caller. A No resultat query task 2610 initiates process task 2611 which drops the alternateline option MIN call and returns control to the check window entry gate2505.

Should query task 2610 result in Yes, process task 2612 is initiatedwhich captures the remote programming system Update session andinitiates process task 2613 which disconnects the alternate line optionMIN call and returns to the Check Window entry gate 2505.

If IXC bypass is in effect, query task 2608 will result in Yes andinitiate process task 2617 which seizes the house line and generatesring voltage to alert the extensions of an incoming call. Process task2617 then initiates query task 2618 which monitors to determine if ananswer from an extension has occurred.

A No result from query task 2618 initiates query task 2619 whichmonitors for the continuing presence of the cellular caller. A No resultfrom query task 2619 exits through process task 2613 described above. AYes result to query task 2617 loops back to the Ring generation processtask 2617.

An answer from an extension will force a Yes result to query task 2618which initiates process task 2620. Process task 2620 connects the houseline audio to the cellular radio to enable conversation. Process task2620 then starts query task 2621 which monitors the call activity. Querytask 2621 will remain in a tight loop until a disconnect event occurs. AYes result to query task 2621 loops back to the input to query task2621.

When a disconnect event occurs, a No result to query task 2621 initiatesprocess task 2613 described previously.

If the alternate line option MIN was not receiving a call, the No resultto query task 2607 initiates query task 2614 which monitors the centraloffice line for Ring Voltage. A No result to query task 2614 returnscontrol to the Check Window entry gate 2505.

A Yes result to query task 2614 starts query task 2615 which monitorsthe house line for answer from an extension. A query task 2615 No resultloops back to the start of query task 2614 to continue monitoring forline Ring.

A Yes result to query task 2615 initiates query task 2616 which monitorsthe answered call for a disconnect event. If the call is active, the Yesresult to query task 2616 loops back to the start of query task 2616 ina tight loop. When the call is completed, a query task 2616 No resultreturns control to the Check Window entry gate 2505.

During an alternate line option module diverted call when the alternateline option is not operating in the LEC bypass mode, Call Activity querytasks 2635 and 2621 use the alternate line option input line interfaceto monitor the central office line for presence of ring voltage. Shoulda call be presented for the house, the alternate line option will issuea call-waiting tone to the house side of the output line interface.

The house line extension user can elect to answer this call byperforming a hook-flash. Alternate line option detection of a hook-flashresponse to an alternate line option call-waiting notification willcause the alternate line option to toggle its output line interface backto the central office line to answer the incoming call.

The cellular call is left up and the called party is effectively placedon hold pending another hook-flash by the house line. Should the callerforget to return to the cellular call on hold, and simply hang up theextension, the alternate line option will seize the output lineinterface and generate ring voltage into the house wiring.

When this ring is answered, the alternate line option module willreconnect the cellular call to the house wiring. Should the cellularcalled party terminate while on hold, the alternate line option modulewill ignore any further hook-flash from the house wiring.

Alternate line option module detection of an unsolicited hook-flashduring an alternate line option completed call in progress will bepassed to the cellular system following cellular protocol.

When the alternate line option module operating mode is engagedfull-time LEC replacement, the alternate line option line interface isalways seized (connected to the house wiring) and never releases. Alltraffic in or out then will be handled by the alternate line optionmodule and the cellular system.

Customer use of the described system is extremely simple and providesnumerous advantages. In purchasing service, the customer has an optionof supporting each of the six handsets on up to three pico stations.Thus, a wide variety of pico station placements is possible, i.e. homeand office, for the individualized handsets needed within a family.

The activation steps by the customer are simple, including only a needto plug in the pico station, place each handset in close proximity,select the handset activation command and depress the activation buttonon the base station.

Following registration, handset use effectively parallels that of astandard wire line phone in that dial tone is introduced as soon as thehandset is turned on and placed off hook. Thereafter, standard wirelessdialing protocol is used.

The special handsets, one for each family member, include select numberand selective ring capabilities, which when used in conjunction with thecall forwarding function of the system, enable each family member toidentify and answer personal calls directed to their individual numberswhen at home.

The display features of the handset always let the customer know whatclass of service is being used and even permit the customers, whenentering the home area, to know how many family phones are registered.

Additional features regulate power use of the handsets to conservebattery power whenever possible, and provide a system with minimalneighborhood interference and eavesdropping exposure.

An additional feature is the availability of the cellular system as aprivate second line for call origination when the pico station isserving another handset within the home area. Obviously, the customeralso directly benefits from a variety of service plans at billing ratesthat meet particular needs.

From a system point of view, the preferred embodiment of the presentinvention provides a multiple mode personal wireless communicationssystem which integrates into and coexists within a radiotelephonenetwork such as a cellular network. This system provides both standardand unique additional services to a select group of customers equippedwith special handsets, without impacting other customers supported bythe network or cellular system. System coexistence is establishedthrough use of a reversed control protocol hierarchy on a minimal numberof reserved cellular channels which are shared by all of the selectgroup of customers in a unique enhanced cordless mode of operation.System integration has been provided through the strict adherence toestablished protocol standards and the elimination of the need forfrequency plan coordination efforts. In addition, the present inventionprovides for the unique application of a standard overhead message withprogrammable contents into the cellular system.

This allows the cellular service provider the means to effectivelymarket its services in the form of zones of coverage which most appealto customers. These zones can be as small as a single cell site or aslarge as the entire system. Therefore, a customer may now purchase aservice package that provides for Local use pricing in zones of interestand Premium use pricing elsewhere. Existing cellular customer equipmentwill ignore the additional overhead message and continue to obtaincellular service.

The special handsets of the present invention automatically switchbetween and operate under existing standard protocols in either analogor digital mode with the standard cellular network. The special handsetsutilize a unique protocol in an enhanced cordless mode when within rangeof their independent, locally interconnected pico cells. In keeping withthe object of providing for a ubiquitous telecommunications system, thepresent invention provides these special handsets with the ability toutilize the cellular network as a private second line for callorigination while the handset is within the coverage of the associatedpico cell.

The unique location analysis method of the present invention, aspracticed by these handsets, inhibits their attempts to communicate withtheir associated pico cells until they are in the appropriateneighborhood. This conserves battery power and greatly reducesunnecessary transmissions on the reserved channels. Controlling suchtransmissions enhances the availability of these channels to carry calltraffic.

Additionally, the incorporation of internal precision dial tone intothese special handsets and the use of dialed number analysis inaccordance with the North American Numbering Plan has created a veryuser friendly and easy to use telephone for the customer. The specialhandset message display screens of the present invention also add to theuser friendliness of the system as demonstrated by the customer'sconstant awareness of which system portion is providing service and atwhat relative cost, i.e. Home--Local--Premium.

In addition, the present invention couples a distinctive ring classfeature to the call forward class feature to enable the customer torapidly identify incoming calls at the pico cell location as belongingto a particular one of the supported special handsets. This isaccomplished by having all telephones connected to the house wiring ringwith the cadence of the desired handset's ring signal. The presentinvention also provides an economic benefit to the service provider dueto the ability of the special handset to be remotely programmed via theunique protocol. This capability allows the special handset to bedistributed through sales channels not currently available to theservice provider which will further reduce the ultimate cost to thecustomer. In addition, the present invention provides these specialhandsets with the capability to recognize and operate with up to threeseparate pico cells providing the customer with the flexibility ofestablishing multiple home system environments. The service providerbenefits by having additional locations where call traffic is off-loadedfrom the cellular network. This traffic off-loading will allow currentcellular networks to deploy the present invention with minimal impact onthe existing customer base.

The present invention provides network transparent pico cells that areactivated and controlled via a framework of overlay cells that operateindependently of the cellular network. As previously explained, thisoverlay framework uses a unique control protocol on said reservedchannels with a use hierarchy that is reversed from cellular.

The unique method of control eliminates the need for the pico cells tocontact, communicate with or become part of the overall cellularnetwork, which allows them to operate transparently to the existingcustomer base supported by the cellular network. The present inventionprovides that each pico cell will consist of a spectrally dynamic,noncapturing, frequency agile, multi-purpose base station that iscustomer installed at customer selected locations. Each pico cellcooperates with the overlay cell framework and supports the enhancedcordless mode of operation of the special handsets. Each pico cell iscapable of supporting multiple handsets and constitutes a separate,locally interconnected, limited coverage wireless communications systemwhich effectively off-loads traffic from the cellular system. This isaccomplished by each pico cell independently handling its registeredspecial handset call traffic through said local interconnect to the PSTNwithout cellular network involvement.

In addition, however, as cellular network traffic capacities increase,an element of the present invention known as an alternate line optionmodule can provide a wireless local interconnect capability. Thealternate line option module is remotely programmable and allows thecellular service provider to selectively transfer or allocate calltraffic to and from the public switched telephone network to and fromthe cellular radiotelephone network, creating a totally wireless system,if desired.

This alternate line option module includes in its programmable operatingcriteria the data needed to internally determine when it will operateand what specific functions it will perform.

As provided in the present invention, the alternate line option modulecan be deployed independently of the rest of the elements as an adjunctto the existing cellular network. This element is effectively anintelligent central office substitute when it becomes active in feedingthe house wiring in lieu of the normal PSTN connection. This ability toprovide a wireless interconnect alternative, while maintaining fullcompatibility with all existing equipment that is currently connected tothe house wiring, will allow the cellular service provider to competeeffectively for the local exchange market.

The present invention also provides service control units and hoststations to facilitate wireless activation and control of each pico celland special handset via the overlay cell framework. These elements ofthe system assure the integrity of each deployment while eliminatingmuch of the manpower previously required. The method of integration tothe existing customer activation system and the secure protocol greatlyreduce the opportunity for fraudulent practices.

The present invention provides for incorporation of the capabilities ofthe remote programming system while eliminating the need for data modemhardware at the terminal equipment (pico cell and handset). Thissimplification of hardware coupled with the enhanced speed of operation,due to the improved data rate provided by the 10K bit channel, has nowcreated an economically viable remote programming process.

What is claimed is:
 1. A method of operating a radio telecommunicationssystem in response to transmission power levels of said system, saidmethod comprising the steps of:identifying a location for a basestation; transmitting, after said identifying step, signals between saidbase station and a radiotelephone unit; permitting said unit to accesssaid system to participate in communication services when the strengthof said signals exceeds an access threshold, said access threshold beingestablished in response to said identifying step; and preventing saidunit from receiving communication services when the strength of saidsignals falls below a drop threshold, said drop threshold beingestablished in response to said identifying step, and said dropthreshold being less than said access threshold.
 2. A method as claimedin claim 1 additionally comprising the steps of:measuring, at said basestation, signal strength of transmissions emanating from said unit; anddetermining whether said signal strength is below a warning threshold,said warning threshold being greater than said drop threshold and lessthan said access threshold.
 3. A method as claimed in claim 2additionally comprising the steps of:sending, from said base stationwhen said signal strength is below said warning threshold, a warningorder to said unit; and annunciating, in response to said sending step,said warning order at said unit.
 4. A method as claimed in claim 3wherein said preventing step comprises the steps of:determining whethersaid warning order has been sent to said unit; and continuing, untilafter said warning order has been sent to said unit, to permit said unitto participate in communication services when the strength of saidsignals falls below said drop threshold.
 5. A method as claimed in claim3 wherein said annunciating step comprises the step of generating anaudible signal.
 6. A method as claimed in claim 5 wherein:said unitincludes a loudspeaker and a microphone; said audible signal isannunciated at said loudspeaker;and said method additionally comprisesthe step of muting said microphone while said audible signal is beingannunciated.
 7. A method as claimed in claim 1 additionally comprising,prior to said transmitting step, the step of selecting, at one of saidbase station and said unit, a channel as being free for use intransmitting said signals by said one of said base station and said unitwhen said channel exhibits a signal level below said drop threshold. 8.A method as claimed in claim 1 additionally comprising the step ofprogramming a memory element, after said identifying step and beforesaid transmitting step, of one of said base station and said unit withsaid access and drop thresholds.
 9. A method as claimed in claim 8wherein said programming step comprises the step of receiving data atsaid one of said base station and said unit, said data defining saidaccess and drop thresholds, and said data being received from a locationremote to said base station.
 10. A method as claimed in claim 1wherein:said drop threshold defines a level at which signals received atsaid base station exhibit sufficient strength to support communications;said method additionally comprises the step of refraining from grantingsystem access to said unit when said unit does not currently have systemaccess and when a signal received at said base station from said unitexhibits a signal strength between said drop and access thresholds; saidpermitting step grants system access to said unit when said unit doesnot currently have system access and when a signal received at said basestation from said unit exhibits a signal strength greater than saidaccess threshold; and said preventing step comprises the step ofrevoking system access to said unit after said permitting step grantssystem access when a signal received at said base station from said unitexhibits a signal strength less than said drop threshold.
 11. A methodof operating a radio telecommunications system in response totransmission power levels of said system, said method comprising thesteps of:establishing access and drop thresholds for a first radiotelecommunications device, wherein said drop threshold is less than saidaccess threshold, and said drop threshold defines a level at whichsignals received at said first device exhibit sufficient strength tosupport communications; receiving data at said first device whichdefines said access and drop thresholds, said data being received from alocation remote to said first device; programming a memory element ofsaid first device with said access and drop thresholds; refraining fromgranting system access to second radio telecommunication devices whichdo not currently have system access when signals received at said firstdevice from said second devices exhibit signal strengths between saiddrop and access thresholds; granting system access to third radiotelecommunication devices which do not currently have system access whensignals received at said first device from said third devices exhibitsignal strengths greater than said access threshold; and revoking systemaccess to said third devices after said granting step when signalsreceived at said first device from said third devices exhibit signalstrengths less than said drop threshold.
 12. A method as claimed inclaim 11 wherein said establishing step additionally establishes awarning threshold, said warning threshold being greater than said dropthreshold and less than said access threshold.
 13. A method as claimedin claim 12 additionally comprising the step of annunciating, after saidgranting step, a warning at one of said third devices when signalsreceived from said one third device exhibits a signal strength at saidfirst device less than said warning threshold.
 14. A method as claimedin claim 13 additionally comprising the step of continuing, after saidannunciating step, to permit said third device to participate incommunication services for a predetermined duration before performingsaid revoking step when said signal strength at said first device fallsbelow said drop threshold.
 15. A method as claimed in claim 11additionally comprising, prior to said refraining and granting steps,the step of selecting, at one of said first, second and third devices, achannel as being free for use in transmitting signals by said one ofsaid first, second and third devices when said channel exhibits a signallevel below said drop threshold.
 16. A method of operating a radiotelecommunications system in response to transmission power levels ofsaid system, said method comprising the steps of:establishing access anddrop thresholds for a first radio telecommunications device, whereinsaid drop threshold is less than said access threshold, and said dropthreshold defines a level at which signals received at said first deviceexhibit sufficient strength to support communications; identifying alocation for said first radio telecommunications device; programming amemory element of said first device with said access and drop thresholdsin response to said identifying step; refraining from granting systemaccess to second radio telecommunication devices which do not currentlyhave system access when signals received at said first device from saidsecond devices exhibit signal strengths between said drop and accessthresholds; granting system access to third radio telecommunicationdevices which do not currently have system access when signals receivedat said first device from said third devices exhibit signal strengthsgreater than said access threshold; and revoking system access to saidthird devices after said granting step when signals received at saidfirst device from said third devices exhibit signal strengths less thansaid drop threshold.